Now that a diplomatic solution seems unlikely, Democrats face a clear choice when Congress votes on the Gulf crisis today. We can contribute to shaping a leadership role for America in a post-Cold War world, or we can persist in an equivocation and malaise that has haunted our party for two decades -- giving Republicans an undeserved lock on foreign policy issues and, as a consequence, the American presidency.

It is time for national Democrats to outgrow the mystique of the anti-Vietnam era and reject the simplistic conclusion, which still lingers in some quarters, that military force is justified only if the United States is directly attacked. We need to debate Republicans on the issues of today -- not yesterday. We need to begin thinking again like a presidential party capable of providing strong leadership in a world far different from that of the 1960s.

There are indeed valid lessons from the Vietnam experience that need to be remembered, and some of them have already been put to good use by Democrats since Saddam Hussein's bloody invasion of Kuwait five months ago. For instance, when the Bush administration's explanations of its policy in the Gulf grew confused, Democrats were right to insist on a clearer rationale for our presence there. We know that a foreign policy -- certainly one that may require the use of military force -- cannot succeed when Congress and the public are ill informed or feel they have been tricked into assenting.

When President Bush's national security team began showing the arrogance of "the best and the brightest," we forced them to discuss their actions with Congress and the country. Recent polls show that, contrary to the fears of the White House, the public's support for the Gulf policy actually began to grow when congressional hearings on the crisis began in December. Such democratic give-and-take, as much as constitutional propriety, is justification for a strong congressional role in foreign affairs.

The lessons many Democrats learned from Vietnam -- that force must be a last resort, that open debate must be encouraged, that our friends and allies must share the burdens and that a firm political groundwork must be laid at home -- have enabled our country to meet the Gulf crisis in a more thoughtful and determined way.

But when such foundations are properly in place, and our vital interests are threatened as they are in the Gulf, Democrats must demonstrate that we are willing to respond to an aggressor with decisive force. Saddam appears to be a man who can comprehend no other language -- a tyrant who appears set on military conquest. A vote by Congress to respond to him with force if nothing else succeeds may be, paradoxically, our only hope to turn him on the path toward peace. And if we must have war, it seems better to face it now than in some unpredictable future.

The sanctions imposed against Iraq may reduce the effectiveness of its military, but there is no sign that sanctions alone will persuade Saddam to leave Kuwait any time soon. And time is not necessarily on our side: the coalition aligned against Saddam cannot withstand indefinitely the pressures working to divide it. Nor is there reason to believe that sanctions alone can reduce the Iraqi dictator's chemical and biological weapons capabilities or stem his drive for nuclear weapons.

Saddam is a sobering reminder for both Democrats and Republicans that, even though we emerged from the Cold War victorious, there are still ambitious figures around the world waiting to test America's resolve and watching to see if a dictator can gain from a brutal crime.

There is also an important lesson to be learned from what has happened in the world in the year just ended. The worldwide surge of support for democracy has also been a remarkable vindication of American values and leadership. The vote by a wide array of countries at the United Nations to support the use of force to dislodge Saddam Hussein from Kuwait was also, in some respects, a referendum on America's role in the world. It said to Democrats: not only is the Cold War over -- so is the Vietnam era.

The writer, a Democratic representative from Oklahoma, is a member of the armed services and intelligence committees.