After Japan's attack onPearl Harbor, the United States declared war (sense 1) on Japan.
(of a governmental authority) To make aformalpronouncement, or sign a legaldocument, that initiates a state of war between onenation and another, usually beforehostilities begin.
2007, Carlos Ramirez-Faria,Concise Encyclopaedia of World History:
Germanydeclared war on France, who reciprocated, on August 3 [1939], and Englanddeclared war on Germany on August 4, when Belgium was already under invasion.
2011, Henry Hampton, Steve Fayer,Voices of Freedom: An Oral History of the Civil Rights Movement:
Leo Lillard, a Nashville native attending Tennessee State University, had become involved in the sit-ins as soon as they started. It was no longer just the students, it was clear that the town haddeclared war on racism.
