A blockade is the act of actively preventing a country or region from receiving or sending out food, supplies, weapons, or communications, and sometimes people, by military force.
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 and the objective may not always be to conquer the area.
Close patrol of hostile ports, in order to prevent naval forces from putting to sea, is also referred to as a blockade.
Most recently, blockades have sometimes included cutting off electronic communications by jamming radio signals and severing undersea cables.
[5][6] Although primitive naval blockades had been in use for millennia, they were limited by the time ships were able to stay at sea uninterruptedly.
[7] The first successful attempts at establishing a full naval blockade were made by the British Royal Navy during the Seven Years' War (1754–1763) against France.
During World War I, the Allies blockaded the Central Powers, depriving them of food and other strategic materials.
Germany's attempted U-boat blockade caused some shortages in Britain, but ultimately failed.
[16] The UN Charter allows for the right of self-defense but requires that this must be immediately reported to the Security Council to ensure the maintenance of international peace.
If the situation so demands, the blockading nation can request that the ship divert to a known place or harbour for inspection.
The latter two countries announced they would actively defend their ships against Brazilian blockaders, while Britain was forced to steer for a peaceful solution between Brazil and Argentina.