While domestic promises and platitudes usually win votes, often it's international realities that shape presidencies. With that in mind, I compared the foreign policy platforms of two men who seem likely to win their parties' presidential nominations -- Democrat Barack Obama and Republican John McCain -- as detailed in essays for the journal Foreign Affairs.

They're eye-opening, except for the candidates' positions on Iraq. McCain will keep troops there for as long as it takes to win. Obama supports a withdrawal timetable in hopes of pressuring the Iraqi government toward political reconciliation. That squares with their campaign rhetoric.

What's surprising is Obama's acceptance of the Bush Doctrine of unilateral pre-emption. Of course, he proclaims he'll exhaust all diplomatic options before firing a shot in anger. But bottom line, he writes: "I will not hesitate to use force, unilaterally if necessary, to protect the American people or our vital interests whenever we are attacked or imminently threatened." There's little qualitative difference in that statement and the policy implemented by Bush/Cheney.

Both would-be presidents pledge to expand the military. Obama would add 65,000 troops to the Army and 27,000 good men and women to the Marines. Enhancing capabilities is at the core of McCain's modernization plan. Special Forces, civil affairs and intelligence capabilities would be expanded during a McCain administration.

Most intriguing in the McCain plan is the creation of a new specialty -- interrogation. Instead of waterboarding, McCain's interrogators would use advanced psychological techniques to get critical information from detainees. Fine, Senator, but keep the waterboarding option open. It works.

President McCain would make the U.S. the world's policeman, literally. He would create a nonmilitary police force that would deploy to prop up nations on the verge of collapse.

Limiting the spread of nuclear weapons gets lip service from McCain, but is a central part of Obama's foreign policy. His administration would increase funding of International Atomic Energy Agency programs, update the Nuclear Nonproliferation Treaty and work toward ratification of the U.N.'s Comprehensive Test Ban Treaty.

Both men call for improving international relations, but McCain goes further by supporting creation of a new alliance, the League of Democracies. The league's primary weapons would be diplomacy, humanitarian aid and economic sanctions. The alliance wouldn't displace U.N. action but would act when that body fails to.

Obama's approach is more conventional. He relies heavily on existing alliances, bolstered by a heavy dose of new foreign aid. To combat a laundry list of economic, political, social and medical challenges, Obama pledges to double U.S. aid to $50 billion annually by 2012. To battle the corruption that has historically rendered a good portion of our aid worthless, institutional reform would be required.

Many of Obama's polices are program-centric, similar to the Democratic Party's approach domestically. For example, Obama would establish a $2 billion Global Education Fund aimed at narrowing educational inequities.

The two candidates treat China differently. Obama sees the country as an emerging power that must be prodded to take on a larger share of economic, security and environmental responsibilities. McCain views China in the context of an eastward shift of global economic and military power.

He doesn't view that shift as a threat. He sees it as an opportunity, given that more people live under democratic rule in Asia than on any other continent. He considers Japan the region's leader and supports its inclusion on the U.N. Security Council. It is China that McCain considers a central challenge. Until China liberalizes its political structure, it should not be considered an ally. McCain views the Chinese military buildup as a provocation and bristles at its recent attempts to exclude the U.S. from many Asia-Pacific forums. McCain writes extensively about the need to institutionalize security and economic agreements with Asian nations. He discusses North Korea's threat thoroughly, but considers it an anomaly.

Like it or not, foreign policy is becoming a bigger part of our lives and should occupy more of our political discourse, a view I'm sure is endorsed by President Bush. After all, he caught last night's election returns en route to the Middle East.

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