By no means am I a reflexive Bush backer. I voted for Senator McCain in the primaries four years ago, and still suspect that he would have made a better commander in chief. As a Blue-Stater, I am more liberal than President Bush on social issues such as stem-cell research and gay marriage. As a fiscal conservative, I’m not happy about his free-spending ways. And I share some of the common dismay about Mr. Bush’s inarticulateness and abrasiveness.

Yet, in the end, I’m a one-issue voter. Having seen firsthand the collapse of the Twin Towers, my vote is predicated upon this question: Who would do a better job of defending America over the next four years?

I am not at all averse to giving a Democrat a shot. In fact, a Democrat might be better able to sell skeptics abroad and at home on the need for toughness. It also would be good for the Democrats to buy into this long-term struggle, just as Republicans bought into the containment policy with Dwight D. Eisenhower’s 1952 election. If a hawkish Democrat like Senator Lieberman had been nominated – dream on – I probably would have punched my chad for him.

John F. Kerry has been doing a credible imitation of a Lieberman-type New Democrat. In the debates, he has sounded tough and focused. He promises not to give a veto to the United Nations over our security and not to wimp out on pre-emptive action. That’s reassuring. Maybe, I’ve been starting to think, this guy wouldn’t be so bad.

Then I read the October 10 issue of the New York Times Magazine, which featured a cover story by Matt Bai on Mr. Kerry’s foreign policy thinking. Mr. Bush has wrongly pounced on the part in which Mr. Kerry is quoted as saying that our goal should be to reduce terrorism to “a nuisance” because we can never completely eliminate it. That’s true, and it’s similar to a point Mr. Bush made in August. What’s objectionable is not Mr. Kerry’s goal, but how he plans to get there.

Mr. Bai infers – though Mr. Kerry is too cautious to come out and say so – that the candidate agrees with his adviser, Richard Holbrooke, who says: “We’re not in a war on terror in the literal sense. The war on terror is like saying ‘the war on poverty.’ It’s just a metaphor.” That’s some metaphor – it killed 3,000 people.

This is not just a matter of semantics. Words have consequences. As Mr. Bai writes, “If Kerry’s foreign policy frame is correct, then law enforcement probably is the most important, though not the only, strategy you can employ against such forces.” Of course, Mr. Bush uses law enforcement tools against Al Qaeda. But he also believes it is vital to wage war on state sponsors of terror and to spread freedom in order to dry up the ideological cesspools that breed terrorism. Mr. Kerry disagrees. “You can’t impose it on people,” he says of democracy, ignoring our success in doing just that in Afghanistan.

Although he is disdainful of democracy promotion, Mr. Kerry has a soft spot in his heart for diplomatic niceties. Mr. Bai quotes a Kerry adviser as saying “only slightly in jest, that Mr. Kerry’s most tempting fantasy is to attend the G-8 summit.” According to the Times article, Mr. Kerry’s first step upon taking office would be to go to the U.N. “to deliver a speech recasting American foreign policy.” This, despite the latest evidence of the U.N.’s glaring failures in Sudan, where it has done nothing to stop genocide, and Iraq, where it allowed Saddam Hussein to embezzle $11 billion from the oil-for-food program. Mr. Kerry also would redouble efforts to reach a deal with North Korea and Iran despite their unwillingness to abide by earlier accords. And he would appoint “a top-level envoy to restart the Middle East peace process” despite the collapse of this approach four years ago.

Mr. Kerry is offering Clinton redux. This focus on diplomacy and law enforcement, on treating Al Qaeda as if it were the Medellin drug cartel, may have been a plausible posture in the 1990s, when terrorism appeared to be a low-level nuisance. But September 11, 2001, changed everything. Now we know that the jihadists would gladly incinerate one of our cities if they could get their hands on a nuclear bomb – and they won’t be deterred by the prospect of being arrested afterward.

Mr. Bush gets it; he was transformed by September 11. His policy implementation has been shaky, to say the least, but at least he has shown a sense of urgency in combating terrorism and weapons proliferation that was missing in the 1990s. Mr. Kerry claims a similar sense of purpose, but he told the Times that the attacks on America “didn’t change me much at all.” That’s a lot scarier than having a president who’s clueless about “the Internets.”

Mr. Boot is a senior fellow at the Council on Foreign Relations and a weekly columnist for the Los Angeles Times, where this first appeared.