Bush 41 sent troops into Iraq; however, he did not commit the crime of "waging aggressive war", to use the wording applied in the Nuremberg trials to the actions of the national leaders who sent their armed forces across established international boundaries without provocation. In the first Gulf War, it was Saddam Hussein who violated that standard. U.S. troops entered Iraq only as part of the military operations taken in response to Saddam's aggression.
Yes, I know, the first President Bush wasn't perfect, and if he'd managed things better, Saddam might never have invaded Kuwait in the first place. That's a different order of magnitude of criticism, though. Under the Nuremberg standards, George H. W. Bush would be acquitted of the charge of waging aggressive war. His son would be convicted.
Beyond that, consider that in 1991 there was a deliberate decision
not to stage a full-fledged invasion of Iraq. Here's how Bush the elder later detailed his reasoning:
Trying to eliminate Saddam ... would have incurred incalculable human and political costs. ... We would have been forced to occupy Baghdad and, in effect, rule Iraq. The coalition would instantly have collapsed, the Arabs deserting it in anger and other allies pulling out as well. Under those circumstances, furthermore, we had been self-consciously trying to set a pattern for handling aggression in the post-cold war world. Going in and occupying Iraq, thus unilaterally exceeding the U.N.'s mandate, would have destroyed the precedent of international response to aggression we hoped to establish. Had we gone the invasion route, the U.S. could conceivably still be an occupying power in a bitterly hostile land.
According to The Memory Hole, this material is from the 1998 book
A World Transformed, by George H. W. Bush and Brent Scowcroft. This particular passage appeared in an excerpt, "Why We Didn't Remove Saddam", in
Time magazine, March 2, 1998. Read the excerpt at
http://www.thememoryhole.org/mil/bushsr-iraq.htm and try to imagine this kind of thoughtful consideration coming from the current denizen of the White House.