Sea lines of communication

Sea lines of communication (abbreviated as SLOC) is a term describing the primary maritime routes between ports, used for trade, logistics and naval forces.[1] It is generally used in reference to naval operations to ensure that SLOCs are open, or in times of war, to close them.

In the American Revolutionary War and the Napoleonic Wars, the SLOCs were, for the most part, in the control of the British Navy. When the British lost control of them during the Revolution, the result was the fall of Yorktown and its biggest army and, ultimately, the war. In the Napoleonic era, maintaining belligerence throughout, the British embargoed and blockaded any country associated with Napoleon, which created large economic hardships and dislocations that ultimately led to the people of France becoming disenchanted with Napoleon.

In World War I and World War II, the British and Germans declared mutual blockade and the Kriegsmarine attempted to close the SLOCs from North America to the British Isles with the use of submarines. In each case the Allies succeeded in keeping the sea lanes open. The Germans in each case failed to defeat the British naval blockade of Germany.

The United States Navy in World War II successfully closed the SLOCs to Japan, strangling the resource-poor island nation.

The importance of SLOCs in geopolitics was described in Nicholas J. Spykman's America's Strategy in World Politics published in 1942.

Had the Cold War turned hot, Europe would have required resupply and reinforcement from North America. Soviet Navy strategy was to close the SLOCs to maximize their numerical superiority in Europe.

China’s Critical Sea Lines of Communication
China’s Critical Sea Lines of Communication. In 2004, over 80 percent of Chinese crude oil imports transited the Straits of Malacca, with less than 2 percent transiting the Straits of Lombok. Click to enlarge. See also: China's String of Pearls

See also


  1. ^ Klein, John J. (2007). "Maritime Strategy Should Heed U.S. and UK Classics". U.S. Naval Institute Proceedings. 133 (4): 67–69.
Allied Forces Mediterranean

Allied Forces Mediterranean was a NATO command covering all military operations in the Mediterranean Sea from 1952 to 1967. The command was based at Malta.

Allied Naval Forces Southern Europe

Allied Naval Forces Southern Europe (NAVSOUTH) was a Component Command in NATO's Allied Forces Southern Europe (AFSOUTH).

Between 1951 and 1953, after the establishment of AFSOUTH, Commander-in-Chief Allied Forces Southern Europe, initially Admiral Robert Carney of the United States, also held the title of Commander, Allied Naval Forces Southern Europe. With the creation of Allied Forces Mediterranean in 1953, a British-led major NATO Subordinate Command that was responsible for maritime operations in the southern region the command and title was disestablished.In 1967 the NATO Military Command Structure was reorganised with the disbandment of Allied Forces Mediterranean. Established in partial recompense was NAVSOUTH, reactivated on 5 June 1967. The first commander of the reactivated organisation was Admiral Luciano Sotgiu of the Italian Navy. Its headquarters was located on Nisida island, Naples, Italy.

NAVSOUTH's tasks were the control of the sea, a 24-hour surveillance of its area of responsibility, the protection of the sea lines of communication, as well as the naval control of shipping in the Mediterranean Sea and the Black Sea.

On 28 May 1969 the future establishment of the Naval On-Call Force Mediterranean (NAVOCFORMED) was approved by the NATO Defence Planning Committee. The ships were to be called together and exercised at least once a year. Later the force was upgraded to standing status and renamed Standing Naval Force Mediterranean. Also formed later was the Mine Counter Measures Mediterranean Force (MCMFORMED)

At the end of the Cold War the structure of Allied Naval Forces Southern Europe was as follows:

Allied Naval Forces Southern Europe (NAVSOUTH), in Naples, Italy, with the following national commands of Mediterranean NATO members:

Commander Gibraltar Mediterranean (COMGIBMED), in Gibraltar, under a Royal Navy Rear Admiral and Flag Officer Gibraltar

Commander Western Mediterranean (COMMEDWEST), under a French Navy admiral, until 1962 in Algiers, then Toulon, after France left NATO's integrated command structure in 1966 the command was absorbed by NAVSOUTH

Commander Central Mediterranean (COMEDCENT), in Naples, under an Italian Navy admiral

Commander Eastern Mediterranean (COMEDEAST), in Athens, under a Greek Navy admiral

Commander South-Eastern Mediterranean (COMMEDSOUTHEAST), under a British admiral in Malta, after the disbanding of the Mediterranean Fleet, the command was absorbed by NAVSOUTH

Commander North-eastern Mediterranean (COMEDNOREAST), in Ankara, under a Turkish Navy admiral (includes the Black Sea)In 2004, NAVSOUTH became Allied Maritime Command Naples.

Australia–Hong Kong relations

Australia–Hong Kong relations refers to international relations between Australia and Hong Kong. Australia has extensive and enduring interests in the Hong Kong Special Administrative Region. The Commonwealth of Australia supports Hong Kong's "high degree of autonomy" under Chinese sovereignty as provided for by the Sino-British Joint Declaration, Hong Kong's mini-constitution, the Basic Law, and in accordance with China's policy of observing "one country, two systems".

Bangladesh Navy

The Bangladesh Navy (Bengali: বাংলাদেশ নৌবাহিনী; Bangladesh Nou Bahini) is the naval warfare branch of the Bangladesh Armed Forces, responsible for Bangladesh's 118,813 square kilometres (45,874 sq mi) of maritime territorial area, and the defence of important harbours, military bases and economic zones. The primary role of the Bangladesh Navy is to protect the country's economic and military interests at home and abroad. The Bangladesh navy is also a front line disaster management force in Bangladesh, and participates in humanitarian missions abroad. It is a key regional player in counter terrorism efforts, and engages in global peacekeeping with the United Nations.

Battle of Dalushan Islands

The Battle of Dalushan (Greater Deer Mountain) Islands (大鹿山等岛战斗) was a battle fought between the nationalists and the communists for several islands and islets just off the coast of Zhejiang, China during aftermath of the Chinese Civil War in the post-World War II era; it resulted in a communist victory.

Order of battle:


The 42nd Column of the Anti-Communist Assault Army


A battalion of the 179th regiment of the 60th Division

Two companies of the 17th Public Security DivisionOn May 29, 1953, a battalion of the 179th regiment of the 60th Division and two companies of the 17th Public Security Division launched their assault on Da Lu Shan Dao (大鹿山岛, "Greater Deer Mountain Island"), Xiao Lu Shan Dao, (小鹿山岛, "Lesser Deer Mountain Island"), Ji Guan Shan Dao (鸡冠山岛, "Rooster’s Crown Mountain Island"), and Yang Yu (羊屿, "Goat Islet") off coast of Zhejiang. At 6:00 PM, People's Liberation Army artillery bombarded Ji Guan Shan Dao and Yang Yu from Zhaitoujiao (寨头角) and Kanmen (坎门) on the mainland. At 7:00 PM, the first assault wave successfully landed on the two islets. Afterward, naval gunboats approached Da Lu Shan Dao and Xiao Lu Shan Dao and bombarded the nationalist positions on the islands. At 9:00 PM, the battle ended with 53 nationalists killed and 186 captured, including the commander of The 42nd Column of the Anti-Communist Assault Army, He Zhuoquan (何卓权). The Nationalists also lost 2 junks, 8 radio sets along with code books.

The communist victory insured further isolation of the nationalist strongholds along the coast of Zhejiang, such as Dachen Archipelago and Yijiangshan Islands, and another nationalist threat to the vital coastal sea lines of communication was eliminated. As for the nationalists, these islands and islets were simply too small to station the large number of troops required for any effective defense. They were also simply too far away from the nearest nationalist stronghold along the coast so it was impossible to reinforce the local garrison in time.


A blockade is an effort to cut off supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo or sanctions, which are legal barriers to trade. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than a fortress or city. While most blockades historically took place at sea, blockade is still used on land to prevent someone coming into a certain area.

A blockading power can seek to cut off all maritime transport from and to the blockaded country; although stopping all land transport to and from an area may also be considered a blockade. Blockades restrict the trading rights of neutrals, who must submit for inspection for contraband, which the blockading power may define narrowly or broadly, sometimes including food and medicine. In the 20th century air power has also been used to enhance the effectiveness of the blockade by halting air traffic within the blockaded airspace.

Close patrol of hostile ports, in order to prevent naval forces from putting to sea, is also referred to as a blockade. When coastal cities or fortresses were besieged from the landward side, the besiegers would often blockade the seaward side as well. Most recently, blockades have sometimes included cutting off electronic communications by jamming radio signals and severing undersea cables.

Choke point

In military strategy, a choke point (or chokepoint) is a geographical feature on land such as a valley, defile or a bridge or at sea such as a strait, which an armed force is forced to pass, sometimes on a substantially narrower front and therefore greatly decreasing its combat power, to reach its objective. A choke point can allow a numerically inferior defending force to thwart a larger opponent if the attacker cannot bring superior numbers to bear.

German Navy

The German Navy (German: Deutsche Marine or simply German: Marine listen ) is the navy of Germany and part of the unified Bundeswehr ("Federal Defense"), the German Armed Forces. The German Navy was originally known as the Bundesmarine ("Federal Navy") from 1956 to 1995, when Deutsche Marine ("German Navy") became the official name with respect to the 1990 incorporation of the East German Volksmarine ("People's Navy"). It is deeply integrated into the NATO alliance. Its primary mission is protection of Germany's territorial waters and maritime infrastructure as well as sea lines of communication. Apart from this, the German Navy participates in peacekeeping operations, and renders humanitarian assistance and disaster relief. They also participate in Anti-Piracy operations.

History of the Republic of Korea Navy

The Republic of Korea Navy was founded on November 11, 1945 as Marine Defense Group after Korea was liberated from the Empire of Japan. The ROK Navy is the oldest service within the ROK Armed Forces. In 2015, the South Korean navy celebrated its 70th anniversary.

Since the Korean War, the ROK Navy had concentrated its efforts on building naval forces against the North Korean navy, which has littoral naval capabilities. As South Korea's economy grew, the ROK Navy was able to locally build larger and better equipped fleets to deter aggression, to protect the sea lines of communication, and to support the nation's foreign policy. As part of its mission, the ROK Navy has engaged in several peacekeeping operations since the turn of the 21st century.

The ROK Navy aims to become a blue-water navy in the 2020s.

Republic of Korea Armed Forces

The Republic of Korea Armed Forces (Korean: 대한민국 국군), also known as the ROK Armed Forces, are the armed forces of South Korea. The ROK Armed Forces is one of the largest standing armed forces in the world with a reported personnel strength of 3,699,000 in 2018 (599,000 active and 3,100,000 reserve). South Korea has one of the highest defense budgets in the world, ranking 10th globally in 2019, with a budget of more than $43 billion U.S. dollars. The South Korean military is ranked as the 7th most powerful military force in the world as of 2019.The Republic of Korea Armed Forces were founded in 1948, following the establishment of the South Korean government after Korea's liberation from the Empire of Japan. South Korea's military forces are responsible for maintaining the sovereignty and territorial integrity of the state, and also engage in peacekeeping operations and humanitarian, disaster-relief efforts worldwide.

Republic of Korea Navy

The Republic of Korea Navy (ROKN; Korean: 대한민국 해군), also known as the ROK Navy or South Korean navy, is the naval warfare service branch of the South Korean armed forces, responsible for naval and amphibious operations. The ROK Navy includes the Republic of Korea Marine Corps, which functions as a branch of the Navy. The ROK Navy has about 70,000 regular personnel including 29,000 Republic of Korea Marines. There are about 150 commissioned ships with the ROK Navy (a total displacement of about 215,000 tonnes). The naval aviation force consists of about 70 fixed-wing and rotary-wing aircraft. The ROK Marine Corps has about 300 tracked vehicles including assault amphibious vehicles.

The Republic of Korea Navy was established as the Marine Defense Group on November 11, 1945 after Korea was liberated from the Empire of Japan on August 15, 1945. Since the Korean War, the South Korean navy had concentrated its efforts on building naval forces to counteract the North Korean navy. As South Korea's economy grew, the ROK Navy was able to locally build larger and better equipped fleets to deter aggression, to protect the sea lines of communication, and to support the nation's foreign policy. As part of its mission, the ROK Navy has engaged in several peacekeeping operations since the turn of the 21st century. The ROK Navy aims to become a blue-water navy in the 2020s.


SLOC may refer to:

Salt Lake Organizing Committee, the organization responsible for the 2002 Winter Olympics in Salt Lake City, Utah

Schenectady Light Opera Company, a nonprofit community theater organization in Schenectady, New York

Secured line of credit, a type of credit source extended to a government, business or individual by a bank or other financial institution

security link over coax, one type of ethernet over coax

Sea lines of communication, the primary maritime routes between ports, used for trade, logistics and naval forces

Source lines of code, a software metric used to measure the size of a software program

Sea lane

A sea lane, sea road or shipping lane is a regularly used route for vessels on oceans and large lakes. In the Age of Sail they were not only determined by the distribution of land masses but also the prevailing winds, whose discovery was crucial for the success of long voyages. Sea lanes are very important for trade by sea.

Soviet Naval Aviation

Soviet Naval Aviation (AV-MF, for Авиация военно-морского флота in Russian, or Aviatsiya voyenno-morskogo flota, literally "aviation of the military maritime fleet") was the naval aviation arm of the Soviet Navy.

Soviet Navy

The Soviet Navy (Russian: Военно-морской флот СССР (ВМФ), romanized: Voyenno-morskoy flot SSSR (VMF), lit. 'Military Maritime Fleet of the USSR') was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy was a large part of the Soviet Union's strategic plan in the event of a conflict with opposing super power, the United States, the North Atlantic Treaty Organization (NATO), or another conflict related to the Warsaw Pact of Eastern Europe. The influence of the Soviet Navy played a large role in the Cold War (1945-1991), as the majority of conflicts centered on naval forces.

The Soviet Navy was divided into four major fleets: the Northern, Pacific, Black Sea, and Baltic Fleets; under separate command was the Leningrad Naval Base. The Caspian Flotilla was a smaller force operating in the land-locked Caspian Sea. Main components of the Soviet Navy included Soviet Naval Aviation, Naval Infantry (Soviet Marines), and Coastal Artillery.

After the dissolution of the Soviet Union in 1991, Russia inherited the largest part of the Soviet Navy and reformed it into the Russian Navy, with smaller parts becoming the basis for navies of the newly independent post-Soviet states.

String of Pearls (Indian Ocean)

The String of Pearls is a geopolitical theory on potential Chinese intentions in the Indian Ocean region (IOR). It refers to the network of Chinese military and commercial facilities and relationships along its sea lines of communication, which extend from the Chinese mainland to Port Sudan in the Horn of Africa. The sea lines run through several major maritime choke points such as the Strait of Mandeb, the Strait of Malacca, the Strait of Hormuz, and the Lombok Strait as well as other strategic maritime centers in Pakistan, Sri Lanka, Bangladesh, the Maldives, and Somalia.

Many commentators in India believe this plan, together with the China–Pakistan Economic Corridor and other parts of China's Belt and Road Initiative under Xi Jinping, is a threat to India's national security. This as such a system would encircle India and threaten its power projection, trade, and potentially territorial integrity. Furthermore, China's support for India's traditional enemy of Pakistan (see: Indo-Pakistani wars and conflicts) and its Gwadar Port is viewed as a threat, compounded by fears that China may develop an overseas naval military base in Gwadar, which could allow China to conduct expeditionary warfare in the IOR. India has since been making moves of various types to counter the perceived threat.

The term as a geopolitical concept was first used in an internal US Department of Defense report, "Energy Futures in Asia" in 2005 . The term is also widely used in India's geopolitical and foreign policy narratives to highlight India's concerns over massive Chinese Belt and Road Initiative projects across southern Asia. According to the EUISS, the formation of Quadrilateral Security Dialogue (consisting of United States, India, Australia and Japan) is a direct result of China's assertive foreign and security policy in the Indo-Pacific region.The emergence of the String of Pearls is indicative of China's growing geopolitical influence through concerted efforts to increase access to ports and airfields, expand and modernize military forces, and foster stronger diplomatic relationships with trading partners. The Chinese government insists that China's burgeoning naval strategy is entirely peaceful in nature and is only for the protection of regional trade interests. Chinese Premiers Hu Jintao and Xi Jinping have both asserted that China will never seek hegemony in foreign relations. A 2013 analysis by The Economist also found the Chinese moves to be commercial in nature. Although it has been claimed that China's actions are creating a security dilemma between China and India in the Indian Ocean, that has been questioned by some analysts, who point to China's fundamental strategic vulnerabilities.


TeLEOS-1 is Singapore's first commercial earth observation satellite launched on a PSLV-C29 vehicle of ISRO from SDSC (Satish Dhawan Space Center) at Sriharikota on December 16, 2015 along with other five satellites developed in Singapore. The satellite is aimed at providing high temporal imagery and geospatial solutions for homeland security and border control; maritime monitoring and disaster management around the equatorial belt. TeLEOS-1 is developed by ST Engineering.

United States Third Fleet

The United States Third Fleet is one of the numbered fleets in the United States Navy. Third Fleet's area of responsibility includes approximately fifty million square miles of the eastern and northern Pacific Ocean areas including the Bering Sea, Alaska, the Aleutian Islands and a sector of the Arctic. Major oil and trade sea lines of communication within this area are critically important to the economic health of the United States and friendly nations throughout the Pacific Rim region.First established in 1943, the Third Fleet conducted extensive operations against Japanese forces in the Central Pacific during World War II. Deactivated in 1945, the fleet remained inactive until 1973, when it was reactivated and assumed its current responsibilities.

Wolfgang Wegener

Wolfgang Wegener (September 16, 1875 in Stettin – October 29, 1956 in Berlin-Zehlendorf) was an officer in the Imperial German Navy, retiring in 1926 with the rank of Vizeadmiral (vice-admiral).

He is noted as the originator of a series of influential works, published between 1915 and 1929, outlining the so-called Wegener Thesis. This thesis criticized the naval strategy adopted by Germany in the First World War, and proposed an alternative strategy based on threatening the sea lines of communication of the United Kingdom with both surface and sub-surface forces. The Wegener thesis is often regarded as a significant contribution to German naval strategy in the Second World War, although the extent to which this was actually the case is disputed.

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