Sea lines of communication (abbreviated as SLOC) is a term describing the primary maritime routes between ports, used for trade, logistics and naval forces.
The importance of SLOCs in geopolitics was described in Nicholas J. Spykman's America's Strategy in World Politics published in 1942.
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.
The United States Navy in World War II successfully closed the SLOCs to Japan, strangling the resource-poor island nation.
The Soviet Navy could potentially threaten and contest Atlantic SLOCs to support ground offensives in Europe.