One of the most unfortunate treaties of modern times was the Kellogg-Briand Pact of 1928 outlawing war as a means of settling disputes among nations.

It took only three years for the first flagrant violation, and in 11 years all the signatory nations were at each other's throats with the onset of World War II. Since then, the cause of disarmament and weapons limitation treaties has been uphill.Still, the Senate did exactly right Thursday night in approving the Chemical Weapons Convention. The CWC attempts to outlaw poison gas among the 164 signatory nations by banning the use, production, development and stockpiling of chemical weapons. Current stocks of such weapons are to be destroyed.

The treaty, as its opponents kept pointing out, is not perfect, but it doesn't have to be.

The CWC will not prevent rogue nations from developing chemical weapons; they wouldn't be rogue nations if they abided by treaties. But the CWC will give other nations the moral and legal high ground and the incentives to take action against those rogue nations.

Further, because of the CWC, no nation will embark on a chemical weapons program as a casual, military afterthought. A nation inclined to develop "the poor man's atom bomb" will now have solid reasons not to. And the verification procedures will give the world an early warning system should any nation still choose to try.

If the treaty achieves only those modest goals, it will be a success. Achieving those goals will, as a practical matter, depend heavily on the United States' vigilant oversight of the CWC and its insistence that the provisions be enforced. The sanctions against Iraq, a nation that has actually used chemical weapons, would have long ago crumbled if not for the United States.

Since World War I, large-scale use of chemical weapons hasn't been a problem, their use held in check because of mutual fear of reprisals in kind and because they are indiscriminately hazardous to both friend and foe.

This psychological and technological stalemate may not always prevail, and for that reason the United States is much better off with this treaty than without it.