Robert G. Kaiser shows in today’s Washington Post what many of us have known for some time: notwithstanding their differences over the wisdom of going to war in Iraq, Barack Obama and John McCain may largely agree on the wisdom of going to war in general.

Neither man wants you to believe that, of course. It behooves them to highlight their differences, both to rally their core supporters, and to make an affirmative case for why they should be chosen by the voters to lead the country for the next four years. These differences are most pronounced in domestic matters: in fiscal policy and on taxes, on health care, and on the benefits of international trade.

But, Kaiser writes, the two candidates share many similar views on national security:

[B]oth have revealed a willingness to commit U.S. forces overseas for both strategic and humanitarian purposes. Both agree on a course of action in Afghanistan that could lead to a long-term commitment of American soldiers without a clear statement of how long they might remain or what conditions would lead to their withdrawal.

Both candidates favor expanding the armed forces, Obama by 92,000 and McCain by as many as 150,000. Both speak of situations when the United States might have to commit its troops for “moral” reasons, whether or not a vital American interest was at risk. Both accept what Andrew Bacevich, a retired Army colonel and professor at Boston University, calls the “unspoken consensus which commits the United States to permanent military primacy” — shared, Bacevich said, by leading figures in both parties.

Obama has worn his opposition to the Iraq War as a badge of honor. And rightly so. His principled stand, taken at a time when precious few politicians were willing to do the same, has allowed him to turn his opponents’ (first Clinton and now McCain) supposed advantage — their experience — into a liability, or at least a nullity. If experienced politicians could make such a colossal blunder as to support a war that now two thirds of all Americans believe to have been a mistake, then what is the value of experience?

But the great unknown remains the lessons that Obama has taken away from the Iraq experience. Was the forcible removal of Saddam Hussein from power a good idea, poorly executed? Or was it a bad idea at the outset, further complicated by bungling in the Executive Branch? Obama has signaled that he believes the latter, but some of his advisers seem to have more confidence in their ability to pull off similar missions in the future — say, for example, against the government in Sudan, as Obama advisers Susan Rice and Tony Lake suggested in late 2006.

Given the continuing influence within the Democratic Party of the so-called liberal hawks, there is even the disturbing possibility that a President Obama would be more prone to military intervention than his predecessor.

That said, John McCain’s continued strong support for the Iraq War is merely one of many examples of his enthusiasm for using our military to solve distant problems. He has adopted a similarly bellicose stance toward North Korea and Iran, and has hinted darkly at a confrontational posture toward Russia that could ultimately result in a ruinous military conflict. In that respect, I wholeheartedly agree with Justin Logan’s deliberate ambivalence in his most recent paper, “Two Kinds of Change: Comparing the Candidates on Foreign Policy”: “The best case that can be made for Senator Obama’s foreign policy is the fact that the alternative to his approach is Senator McCain’s.”

It is possible, perhaps even likely, that the lingering effects of the Iraq War will greatly limit the next president’s enthusiasm for foreign military intervention. But nothing that either candidate has said during this campaign gives me sufficient assurances that that is the case. Foreign policy has generally been pushed aside during this long campaign, an understandable shift given the current economic climate. But it is not too late for both men to clarify their views on the use of force, and to explain how they might differ from their opponent.