What? If Congress never officially declared war, it's an undeclared war (usually just called a conflict, such as the case was with Vietnam).
If you're referring to Congress being able to just pass a bunch of statutes and never formally declare war, it's still an undeclared war.

That was the ORIGINAL goal but as the war spread out it was ever changing. I meant to say no concrete goal

We did, the main objective was the stop the spread of communism in Vietnam, and to not have a domino effect in the rest of the area. Vietnam is now communist, so America did lose its main objective.

----------------------------
The Vietnam War was not a war it was a military-conflict . So America never lost a war, and has not been in a war since WW2.

1 and we won We're otherwise relatively peaceful (at least with other countries).

Loads lol. Not a good thing is it now !!

Well after reviewing my history book, there are mixed results from scholars about who won the war. I would agree with the scholars saying it was either a stalemate or a win for America. Although the objective of containment was not met, after Americans saw how the war was not beneficial and it became unpopular, the objectives changed to getting all troops out of Vietnam through Vietnamization because no one supported the weak government of South Vietnam. It was successful in doing that and politically it put America back in their place as the most powerful country in the world. So politically, it's a win for America. For the actual war, it was a stalemate since America never technically was in war, we just aided South Vietnam until we let them fight their own fight. They ultimately lost, but also the objective was to stop the "domino effect" of communism and no other country in that region was taken over by the Soviet Union through communism. Because that objective was also met, it could be seen as a win for America.

Basically. I took AP US History too. Got a 4, only because they decided to talk about the late 80s and 90s when they said they weren't. The US never lost a war they officially declared, the Korean and Vietnam, and everything after were conflicts brought by the President and supported by the US. The President is the Chief of the US military so he can move troops around. This is the reason why Mexico declared war on America (The President did this to make Mexico look like a bad guy). AP US was such a fun class.

I hate to bring up my military history but I can use it as an example because what we are going through in Afghanistan is very similar to what happened in Vietnam. When I spoke about losing the war, I didn't mean in battles but politically and strategically. In Afghanistan, a majority of the battles especially in the north we have been winning, but where the problem arises is training the Afghan forces to fight the Taliban. I'll give you an example. We went out on a patrol and training mission to a nearby Afghan National Police post to train them on basic first aid skills. But when we started to train them they were more interested in us giving them blankets than learning the skills that would help them save their lives. It's those small things that make the war difficult: making them actually want to win a war. That is the hard part.

Like every single one.

Directly? Paraguayan War (win)
Indirectly? World War I and II (win)

The President commands the armed forces and therefore has equal power in deciding which wars to fight, so I'd personally count those wars in the Middle East. You could arguably also count the "War on Terrorism", but that one's more abstract.

Anyway,

W - 1756-1763, Seven Years' War (Britain)
Or French-Indian War, which spanned 1754-1763. This one was technically won with Britain. Really the war was between Britain and France, though, and the colonies were simply caught up in the crossfire.

W - 1775-1783, Revolutionary War

T - 1812-1815, War of 1812
Technically, the War of 1812 was settled between the two countries. If you ask me the United States got the better half of the deal, but, nonetheless, it still was not a true victory.

W - 1846-1848, Mexican-American War

W - 1861-1865, Civil War (Union/North)
I count this as a "win", since a "loss" would mean that the South/Confederacy would secede and become its own nation; also, given the involvement of Britain, the successful secession of the South would be a victory for the UK over the Union.

W - 1898, Spanish-American War

W - 1914-1918, World War I (Allies)
In all fairness, the United States only joined in 1917. However, the involvement was still pretty crucial to victory.

W - 1939-1945, World War II (Allies)
Again, the United States joined halfway through, but the involvement here was much larger than the previous world war.

W - 1950-1953, Korean War

L - 1956-1975, Vietnam War
Contrary to what was said earlier, this war is NOT still going on. In 1973, the United States withdrew its remaining troops from South Korea, which fell two years later to communist North Korea. The US might have continued if the public weren't so vehemently opposed, but this was an embarrassing and pride-breaking loss.

W - 1990-1991, Persian Gulf Wars

N - 2001~2014, War in Afghanistan
N - 2003-2011, War in Iraq
Obama withdrew the remaining troops from Iraq late last year, and the remaining troops in Afghanistan are planned to leave by 2014; although you could argue the US has set/is setting up governments that function kinda, sorta on their own, the "winnability" of these ones is shaky at best, so I gave them an "N" for neutral.

Note that I also didn't count any wars that involved the United States colonies pre-Revolutionary War (except the massive French-Indian/Seven Years' War), and I also didn't count the numerous wars involving Native Americans. Yes, these are very important to American History, but I'm not taking the time to list each individual one.

We could quibble all day about the individual battles or what scholars argue, but the Vietnam War was a colossal embarrassment to the United States. Any post-WWII pride the US still had was crushed rather brutally. Also, after the war, Americans were forced to contemplate whether or not it's their duty to involve themselves in others' affairs (a topic that is still debated today).

The President HAS NO POWER in deciding a war. By law Congress can declare war, the only thing the president can do is move troops around. A conflict is NOT a war. A war will involve heavy involvement with the economy. Meaning rations will be given out, all effort will be push for making weapons, armor, and other military needs.The US economy will actually be going up, since everyone will have a job of some sort aiding the war. There will be factories working and such, in other words. There will be less products like consumer cars, tvs and other consumer items, and more industrial and military items being made. In a conflict its pretty much what goes on now, the government will put a little effort to aid the allies, and it will most likely be funded by the UN and other nations.

The US has not been in a war, or had a war economy since WW2. And the conflicts you stated above are not WARS. Congress never declared it, its a conflict. The OP asked to state WARS not conflicts. The French and Indian war should not even be up there, because the US was not even a country. It was still a British colony.

What kind of logic? A war is only a war unless there are rations and everyone is involved in it? Lol what? You realize that would disqualify the Spanish American War, the Mexican-American War, The War of 1812, and even the revolution.

About the "It's not a war unless congress declares a war" thats not what war means by definition. Am I pretty sure the OP is more concerned with the definition of the word rather than what the constitution says. In actuality, the constitution does not define the word war. to make it legal. Article One, Section Eight of the Constitution says "Congress shall have power to ... declare War". However, that passage provides no specific format for what form legislation must have in order to be considered a "Declaration of War" nor does the Constitution itself use the term "Declaration of War". Congress has in fact authorized wars, through legislation, since WW2.

You seem to be confusing the words "formal", "declared", and "official" to mean the same thing. They do not in this context, legally speaking.

Congress authorized LBJ to use military action in Vietnam to protection the south Vietnamese by any means neccesarily. That is a de facto declaration of war.

That's what a stalemate is.

Too many to count

Australia was in WW1, WW2, Korean War, Vietnam War, Afghanistan, Iraq and (I think) the Gulf War.