PASSEX

A PASSEX is a U.S. Navy term for a "passing exercise". Almost any US military term in all capitals ending in ...EX is some type of an exercise.

A passing exercise is done between any two navies for the official reason of ensuring that the two different navies are able to communicate and cooperate in times of war or humanitarian relief. Common drills might include flashing light drills, semaphore drills, and flaghoist drills. In more modern times, navies within a very close alliance might include much more electronic and digital cooperation including using electronic communications and target acquisition. Some exercises between the French and US navies (particularly in support of the war in Afghanistan) have included carrier-based fighter-bombers "touching down" (landing then taking off) on each others carriers in order to ensure interoperability.

While the official reason of a PASSEX is to practice cooperation, various unofficial reasons might be to "show the flag" (show the power of a nation through a public display of naval power) or other political or diplomatic reasons.

Recently Indian navy undertook a (PASSEX) exercise with Turkish navy on 10th and 11th july 2011.