North Korea likes Senator John Kerry. Radio Pyongyang broadcasts the Democratic presidential candidate's speeches along with the regime's predictable denunciations of U.S. President George W. Bush. And the North Koreans are hardly alone. Opinion polls across the globe reflect deep discontent with the current White House occupant. After all, statements such as “working with other countries in the War on Terror is something we do for our sake—not theirs” are bound to irritate citizens and leaders of other nations. By contrast, non-Americans are likely more at ease with a U.S. leader who says “I believe in the international institutions and alliances that America helped to form and helps to lead.”

But be careful what you wish for. The first assertion is Kerry's, and the second comes from Bush. Although such statements may not accurately represent Kerry and Bush's natural proclivities, they may reveal more about the foreign policy of the next U.S. administration than any position paper intended to underscore the candidates' differences. Indeed, these comments by Kerry and Bush highlight a paradox that the candidates and U.S. voters alike are reluctant to recognize: If reelected, Bush will have difficulty sustaining the foreign policies of his first term, whereas a first-term Kerry presidency is bound to emulate some of Bush's more aggressive positions.

Imagine if Bush wins in November. In a second term, the president would discover that large-scale preemptive wars of choice are no longer an option. Despite major increases in military spending during Bush's first term, the U.S. military now finds itself seriously overstretched in terms of troops, funding, and operational capabilities. And if anyone thinks that recruiting foreign allies for the Iraq invasion in 2003 was difficult, doing so in support...