The U.S. invasion of Afghanistan in 2001 really was criminal, and by that I mean that it violated international law. Hear me out:
The attack was based on the Taliban government refusing to turn over Osama bin laden to us. They agreed to turn him over to another country, but not the U.S. But, that wasn't good enough for George W. Bush. And think about it: if Bush and his cronies really thought the Taliban was involved in the 9/11 attacks, they wouldn't have settled for just getting bin laden, would they? Of course not. So, the very fact that Bush was going to leave the Taliban alone if they handed over bin laden tells you that he knew the Taliban was not involved in 9/11.
But, did Bush have the legal right to attack and invade Afghanistan just because they wouldn't turn over bin laden? Well, he sought approval from the UN, and they wouldn't grant it. So obviously, they didn't think it was legal. But more important, THE UNITED STATES DID NOT HAVE AN EXTRADITION TREATY WITH AFGHANISTAN AT THE TIME. So, we had no right to attack them. Does the UK have the right to attack Ecuador because they won't turn over Julian Assange? How would you like it if they bombed the Ecuadoran Embassy?
What makes it worse is that Bush didn't provide one iota of evidence to the Taliban against bin laden. They politely asked for it, but he refused.
So, they were shown no evidence. They had no extradition treaty with the U.S. And they were a sovereign country. So, did they have the right to not turn bin laden over? Yes, they most certainly did. They had every legal right.
And consider this: George W. Bush bought a huge spread in Paraguay. Why Paraguay? Because Paraguay doesn't have an extradition treaty with the U.S. So, if he has to make a hasty retreat out of here, say, if pressure mounts to arrest him for his war crimes, he's not worried that the U.S. is going to attack Paraguay to get him because we don't have an extradition treaty with Paraguay. He bought nearly 300,000 acres. Here's a pic. Nice land.
So, did George W. Bush have the legal right to attack Afghanistan and start a war? Of course not. He had only the right that every bully has.
So, why didn't the U.S. Congress stop him? The Constitution says that only Congress can declare war. But, when Harry Truman put the U.S into in the Korean War without Congress declaring war, that put an end to that Constitutional provision. From that point on, Presidents have put us into every war. It's almost as though the Constitution got instantly amended. The last country Congress declared war on was Nazi Germany.
We have killed hundreds of thousands in Afghanistan. But, the whole war was justified on the basis of one thing: 9/11. So, even if you believe the official story of 9/11, including the part about bin laden (and I and 3000+ architects and engineers don't), how many of the hundreds of thousands that we've killed had anything to do with 9/11? I hope you realize that, even granting everything the U.S. government claims, the number is so small that it is statistically equal to zero.