I believe it has been a very long time since America had a formal declaration of war.
Truman referred to the Korean War as a “police action,” and he invoked UN authority when the Soviets walked out and the Security Council passed a resolution.
Congress sometimes gave approval of one sort or another, and sometimes not.
Perhaps someone can correct me, but although we have been in numerous armed engagements all over the world, large and small, from the Bay of Pigs to the Berlin Airlift to Grenada to Panama to Vietnam to Afghanistan to Nicaragua to the Horn of Africa to you name it, none involved formal declarations, and many only received congressional approval after the fact, if at all.
I don’t think it’s clear from the Constitution whether there must be a formal declaration, and the president has certain emergency powers that do not require immediate congressional approval, although congress does have the clear right to withhold funds.
Even there, Reagan managed to continue supporting the Contras after congress pulled the funding plug by means of Iran Contra and Mena, both more than a little shady but I think justified in the circumstances.
World War II was the last.
Truman referred to the Korean War as a “police action,” and he invoked UN authority when the Soviets walked out and the Security Council passed a resolution.
Correct. Though US forces made up the bulk of the fighting men in the theater, it was a UN mission, not a US one. The US was not at war with North Korea; South Korea was attacked by North Korea, and the UN stepped in to assist. Ditto in 1991 -- the US was not at war with Iraq, but was part of an international coalition that went in to help Saudi Arabia and Kuwait.
A formal declaration of war is a tricky political move. Declaring war necessarily means recognizing another government that you're declaring war on. In Korea, in Afghanistan, and for that matter in the Civil War, the US could not formally declare war, because recognizing the enemy government would undercut the entire rationale behind the war. The US could not declare war on the Kim regime in Pyongyang, or on the Taliban, or on the Confederacy, because to do so would be to legitimize them.
I don’t think it’s clear from the Constitution whether there must be a formal declaration, and the president has certain emergency powers that do not require immediate congressional approval, although congress does have the clear right to withhold funds.
It's clearly unclear. As commander in chief, the president clearly has the power to send troops and call up the militia in cases of invasion or insurrection. The very first president, George Washington, did just that to combat the Whiskey Rebellion.
To clarigy the gray areas in the Constitution, Congress in the wake of Vietnam passed the War Powers Act. No president has accepted its restrictions, but they've all stayed within its terms. No president and no Congress has pressed the point, so there's never been a test case.