A LACK of consensus is no excuse for a lack of leadership, Britain's Margaret Thatcher once remarked. In a compelling speech on Iraq and terrorism Friday morning, Vice President Dick Cheney took her one better: He showed that he realizes that, in the War on Terror, the failure to lead in the face of political opposition could be catastrophic.

In a media blitz reminiscent of the 3rd Infantry Division's swarm on Baghdad six months ago, Cheney and other White House luminaries are reminding us that the world is still a treacherously dangerous place - and we're still at war.

The administration's efforts to explain the challenges of Iraq is an uphill fight, but a necessary one. The White House faces an American public that agreed that Saddam Hussein should go, but is now not quite sure how reconstructing Iraq supports the War on Terror.

The veep brought his audience at The Heritage Foundation around to the steely cold reality of today's international security environment: "Terrorists are doing everything they can to gain even deadlier means of striking us. From the training manuals we found in the caves of Afghanistan to the interrogations of terrorists that we've captured, we have learned of their ambitions to develop or acquire chemical, biological or nuclear weapons." (Saddam Hussein could have aided those aspirations.)

This is a new threat: Terrorists' goals have not traditionally been ones that would benefit from weapons of mass destruction (WMD). In the past, an unspeakable WMD attack - meaning contaminating their own soil, and killing or alienating thousands of would-be supporters - wouldn't advance their agenda. (Think, for instance, of the IRA doing this in Northern Ireland - completely unproductive.) But al Qaeda is different, and there is a new, unmistakable terrorist preference for causing a large number of casualties, as evidenced by attacks on airliners, large office buildings, housing compounds and hotels across the globe. WMDs make achieving that sordid goal just that much easier. (And America is in the crosshairs.)

Back to the veep: "If terrorists ever do acquire that capability - on their own or with help from a terror regime - they will use it without the slightest constraint of reason or morality." There will be no warning and the result: tens of thousands, or even hundreds of thousands of American lives lost in a single nightmarish day.

Cheney's assessment of the terrorist threat two years after 9/11 is sobering. From Afghanistan to Iraq to Southeast Asia, the struggle continues. President Bush's infamous Axis of Evil (minus one charter member) has been replaced by a veritable Devil's Triangle - rogue regimes, terrorists and weapons of mass destruction.

Today, it is not large armies that pose the most serious threat to the United States, our friends and allies. The threat of an amoral rogue state, such as North Korea or Iran, placing WMDs in the slimy paws of ruthless terrorists is the greatest threat to our national security today. We can't ignore it - or wish it away. Even the president's critics don't regret the fact that Saddam Hussein can no longer make or transfer these hellish weapons.

As Cheney said at Heritage, "If the threat from terrorists and terrorist states are permitted to fully emerge, all actions, all words and all recriminations would come too late." The United States must be proactive and continue to take the fight to the enemy. Anything less is unacceptable. Terrorism is a blight that must be excised.

If the United States had dealt decisively with Osama bin Laden (say, a major covert paramilitary operation against his camps in Afghanistan) after he bombed two American embassies in Africa (1998), or the USS Cole in Yemen (2000), the world might well be a different place today.

It is clear: Yesterday's over-cautious, reactive, ad hoc foreign policy doesn't work. In the rough and tumble of today's international politics, it's lead, follow - or get the heck out of the way. The stakes are just too high.

Just as at other important junctures in our nation's history, we, as Americans, have a choice: We can take the steps necessary to ensure our security, or we can remain idle and hope for the best. Be warned: Hope is no sound foundation for national-security policy.

Some decisions we make in the War on Terror will be unpopular at home or abroad, but opinion polls are a terrible basis for executing foreign policy.

The American people have a right to know and understand our domestic and international actions, and the White House is addressing this through its outreach campaign. But we also elected a president to lead - and in times like these, lead he must.

Peter Brookes is a senior fellow for National Security Affairs at The Heritage Foundation.