Although under the war powers resolution act of 1973 the president must consult congress before declaring war or sending troops into hostilities, successive presidents have used their power as commander in chief to avoid consulting congress, with the exception of

The correct answer is Congress belatedly passing a resolution authorizing the president to use military force against Iraq in 1990

Before that, presidents managed to use loopholes in the regulations in order to start or manage war efforts worldwide. This included things like Vietnam, Korea, Afghanistan, or similar. Only when the war in Iraq began did the congress made a joint resolution to officially support the war effort.