At 74, Norman Podhoretz is back – not that he has ever been away.

A generation ago, Mr. Podhoretz, then the editor-in-chief of Commentary, wrote “The Present Danger,” a book about U.S. foreign policy and America’s place among nations. Ronald Reagan loved it, and when Reagan won the Republican nomination for the presidency, the book became a must-read in the corridors of power and was known as the new administration’s foreign-policy Bible.

This summer, Mr. Podhoretz wrote another: “World War IV: How It Started, What It Means and Why We Have to Win,” published not as a book, but as a pamphlet-length (30,000 word) article in Commentary. Unlike “The Present Danger,” which proscribed a new policy going forward, “World War IV” is a brief in defense of the policy President Bush committed to just after September 11,2001.Mr.Podhoretz says he wrote the essay to step back from “the relentless pressure of events … and the daily barrage to piece together the story of what this nation has been fighting to accomplish” since that day.

Mr. Podhoretz argues that the fight is a “great struggle into which the United States was plunged by 9/11 [and] can only be understood if we think of it as World War IV.” He places it in the broad sweep of history that started when Hitler threatened Europe in the 1930s and says what most people still call the Cold War is better described as World War III. Mr. Podhoretz is advancing the Bush Doctrine; it recognizes the fight against terrorists as part of a global struggle that will involve not just armies, but other forces as well, and which could take years to win. Indeed, he emphasizes that “Iraq is only the second front to have been opened in that war: the second scene, so to speak, of the first act of a five-act play.”

This doctrine – in contrast to the Truman Doctrine, which unfolded gradually – “was pretty fully enunciated in a single speech, delivered to a joint session of Congress on September 20, 2001.”What the president did in that speech and all his elaborations since is to change the nation’s attitude and fighting stance against terrorism, which was essentially unaltered by Presidents Nixon, Ford, Bush (the first), Clinton, and even Reagan.

While the Bush Doctrine was wildly popular at first, it is now under siege, not just by left-wing academics, but even by the mainstream press. But for Mr. Podhoretz the September 11 attacks transformed the president from a leader without an apparent vision to one who could realistically claim to be “following in the footsteps of Ronald Reagan.”

His current article has already gained enough currency that when Time magazine interviewed President Bush, the interviewer asked specifically whether the president agreed with Mr. Podhoretz’s current thesis that we are at the beginning of a long, multifront war. If Mr. Bush had heard of the article he didn’t let on – “I’m not the historian. I’m the guy making history” – but White House sources confirm “World War IV” is being read and appreciated by policy-makers.

Given that the Bush Doctrine already has an associated military moniker – the War on Terror – isn’t calling it “World War IV” a least a little incendiary? Mr. Podhoretz denies the suggestion. “I think I’m being descriptive,” he says. “I don’t understand what’s inflammatory about it.”

He says the article could have been published as a short book, but there would have been too many delays. The article appeared just before the Republican National Convention in New York. Mr. Podhoretz, a lifelong New Yorker, did not attend the convention, though he did wind up at several of the parties surrounding it.

He says he doesn’t really see himself having a role in “partisan politics in the narrow sense.” Though he is a strong supporter of Mr. Bush, “I don’t see myself as a Republican,” he says. He does involve himself, as he has throughout his life, in the larger issues, and he hopes his writing will impact government policy in the long run.

“World War IV” advocates a government policy that is already in force, and that Mr. Podhoretz says he believes will necessarily stay in force no matter who is elected president in November. But he says that even the president has become less insistent on the Bush doctrine, perhaps because of the upcoming election. Though the policy remains in effect, “Even [leaders] need to be reminded what they’re up to.”

But will his argument impact policy? That’s harder to say. “It’s very difficult to influence people in office. Most don’t have time to read,” he says, adding that “they [come to power] carrying the intellectual capital they have accumulated before.”

A big event like September 11, though, can prove an exception to this rule. It “will shake things up for people in power just as it will for everyone else.” Without the Al Qaeda attacks there would, of course, have been no need for the Bush Doctrine. Even if some policy-makers might have been itching for a chance to take on Iraq and the Arab world in general, only catastrophe could created consensus.

In the years since September 11, there have been several articles that have had a dramatic impact on policy-makers in the government. Just one month after the attacks, Fareed Zakharia wrote an article in Newsweek titled, “The Politics Of Rage: Why Do They Hate Us?” arguing that the United States should focus on political reforms in the Arab world as a counterweight to fundamentalism and its calls for holy war. Last year, Robert Kagan wrote in Policy Review a piece called “Power and Weakness,” in which he argued that there is a fundamental divide between Americans and Europeans in attitudes about the use of power. These theses have resonated in the decision of the United States to fight the Iraq war, with political reform as one of the goals and without help from continental allies.

Mr. Podhoretz’s essay seems the latest key interpretation of ongoing events. New York Times columnist William Safire and former CIA director R. James Woolsey have both called it “brilliant” (though Mr. Woolsey adds that it was Eliot Cohen, a professor at Johns Hopkins, who first used the term “World War IV”). Mr. Podhoretz says the reaction to the article has been as effusive as anything he has written in a 50-plusyear writing career.

It is too early to predict what full impact of the essay will be, but Mr. Podhoretz is sticking to the long view. His hope in writing was simply to steel the administration for the long battle. His article makes the point that the problem of Islamic terrorism has been festering for a generation, and he urges that a long struggle will be needed to “[drain] the swamps not of poverty and hunger but of political oppression ” in which the disease of anti-Americanism spreads even in the short run. In recent months, Mr. Podhoretz thinks, there has been some unfortunate reluctance in the Bush administration, perhaps caused by a need to please the voters. “He is a politician running for office and he has to take account of this fact.”

Mr. Podhoretz wants to take the war several steps further, though he is unwilling to dictate necessary steps to the president.

If there is a war on, does that mean the United States should invade another country, such as Iran or Syria? Mr. Podhoretz calls such questions tactical, and says, “I don’t have any strong views,” adding, “That’s for the people who are running the show.” As for Iraq’s weapons of mass destruction, he says he believes they are still hidden or were moved to Syria. But whether they are found or not does not change the need to attack Muslim terrorism whether it is secular or the product of religious fundamentalism, as they are both parts of “a two-headed monster.”

If Mr. Podhoretz is agnostic about tactics, he is steadfast in his commitment to broad strategy. He remains as he has been, an unyielding warrior in the battle of ideas.

Mr. Ackman is a senior columnist at Forbes.com