AS THE NATION goes to war, the American people are doubtless as one in their preoccupation with those fighting for them, notwithstanding the political differences that have animated the continuing national debate. Now that the president has made the decision, he as commander in chief has the responsibility to spend this treasure with the utmost care consistent with the purpose of the action. This is how in the first instance the president will be judged. He gave every evidence in his somber speech to the nation last night that he intends to fulfill this commitment.

Mr. Bush, to us, made a compelling case. There can be no question of the threat Saddam Hussein has posed to the American interest in an orderly world. Not only did he invade a sovereign state, rape it and remove it from the map -- an act of total aggression though perhaps not in itself enough to distinguish him from all other tyrants. What made that threat distinctive was the combination of his strategic location, his grandiose ambition and his ruthlessness and hatred of the West, taken together with the wealth and weaponry to fulfill his purposes. Saddam Hussein hoped and had the capacity to go on from Kuwait to destabilize and dominate a region crucial to world equilibrium.

The president announced that British and Saudi aircraft joined Americans in the first strike. Still, questions about the American share of the burden and the timing of the military action now begun will probably outlive the beginning of hostilities. But politically these questions have been addressed in the best way that a democratic society true to itself addresses fundamental issues of public policy: over a period of months, President Bush submitted his choices to two separate but worthy partners in policy, two exacting boards of review. He went to the United Nations: particularly since Vietnam, there has been in this country and abroad a palpable craving to test diplomatic options and then, if military action is deemed necessary, to conduct it with international blessing. Then he went to the forum that necessarily counts most in the American system, Congress. In the two places, not his every tactic but nonetheless the thrust of his policy was explored, weighed and finally approved. The studied and common judgment was that Saddam Hussein had left no feasible and acceptable alternative to the fateful war that is now underway.