President Obama’s new national defense strategy is a budget exercise masquerading as strategic plan. It rationalizes and double talks its way through an explanation that barely disguises the politics involved.

Mr. Obama always made clear that he planned to decrease defense spending. That campaign began in earnest in April when he told Pentagon leaders to find another $400 billion in cuts, on top of $400 billion he already had imposed. He announced that these savings would be found by reviewing America’s national defense strategy.

We just got that “review.” Last week, Secretary of Defense Leon E. Panetta released “new strategic guidance” that will “preserve our ability to conduct [military] missions we judge most important to protecting our core national interests.”

Don’t be fooled by all the highbrowed talk of military strategy. This is mainly a budget exercise intended to justify the cuts promised in April. It is no coincidence that, according to many defense experts, the new plan likely will shrink defense by $487 billion - about the same amount that Mr. Obama promised last year. (The numbers won’t be certain until his fiscal 2013 budget request is released.)

Mr. Panetta surely knows this better than anyone. He said last week that “savings … must be driven by strategy and rigorous analysis, not by the [budget] numbers alone.” Note that word “alone.” He knows the budget crunch is driving this strategy. He said as much in his news conference when he declared, “Congress has mandated that we achieve … defense savings.” It’s true that Congress is partly to blame, but the president is the one forcing the drop in the defense budget.

Mr. Obama is trying to make a strategic virtue of a political play. It’s not just about saving money to fund his domestic priorities. It’s about playing to his anti-war base. This strategic review makes clear that Mr. Obama is against large-scale stability operations such as Iraq, which he predicts are now things of the past. This is what the Pentagon meant by saying U.S. forces will “no longer be sized to conduct large-scale, prolonged stability operations.”

How convenient. It’s supposedly the strategic “future” mandating defense cuts, not Mr. Obama’s political agenda. What better way to make absolutely certain our armed forces will not be able to engage in “large-scale stability operations” than by denying them the capability to do so.

When Mr. Panetta says future large-scale military campaigns will “recede,” he acts as if they will not be needed. But he no more knows what the future will bring than anyone else. Yet he lays out long-range cuts to programs that could take years or decades to reverse. Defense planning should be about preparing for an unpredictable future, not pretending you can foresee it. Anything less is pretending to be soothsayer - and gambling with the nation’s security.

Chairman of the Joint Chiefs of Staff Gen. Martin E. Dempsey seemed to sense this when he said last week, “We do accept some risk, as all strategies must.” Yet the risks imposed by this strategy aren’t because of the budget crisis. They are imposed by the administration’s political agenda.

Mr. Obama’s strategy is based on the false assumption that excessive defense spending is responsible for our government’s fiscal crisis. The facts say otherwise. Today, we spend about 5 percent of our gross domestic product on defense. In 1965, we spent about 7.4 percent. By comparison, spending on Social Security, Medicare and Medicaid has grown from 2.5 percent of the GDP in 1965 to roughly 10 percent today. And these federal health care and retirement entitlements are projected to absorb all federal revenue by 2049.

The risks imposed by Mr. Obama’s new strategy are unnecessary. They are a choice - the choice of a president whose political objective is to fund his domestic agenda by shortchanging defense. Sadly, Congress is complicit. But we should remember that it is the president, as commander-in-chief, who is primarily responsible for the nation’s security.

Kim R. Holmes, a former assistant secretary of state, is a vice president at the Heritage Foundation