The term is sometimes used to include any disagreement or conflict fought about without an official declaration.
Under customary international law, it is not necessary to declare war—simply beginning hostilities is sufficient to make belligerent intentions clear.
[2] There is no specific format required under United States law for the way an official war declaration will be structured or delivered.
[5] On at least 125 occasions a US president has employed military forces without authorization from Congress.
[6] One of the most significant of these occasions was the Korean War, where the United States led a peacekeeping United Nations force to stop North Korea's invasion against South Korea.