Campaigns, be they political or military, are waged to be won, and the current American presidential campaign is no exception. The Democratic and Republican candidates are doing all they can to distinguish themselves from an unpopular incumbent president and from one another in the remaining weeks before Americans vote.
For good reason, much attention is focused on foreign policy differences between the two nominees, which in many areas are both obvious and considerable. Still, it is possible to discern some similarities between them, in part because some of their disagreements are not as pronounced as they seem, and in part because the constraints that the next president of the United States will face are certain to limit what either man could do in office.
Consider Iraq, the most divisive issue in US politics for the past five years. Barack Obama regularly points out that the decision to go to war was deeply flawed; John McCain emphasises how much things have turned around since early 2007, when US troop numbers were increased and US strategy revised. Observers could be forgiven for thinking that they are speaking about two entirely different conflicts.
But what about the future?
No matter who wins this November, it is clear that Iraq will not dominate US foreign policy in the years ahead to anything near the degree that it has in recent years.
We are entering the post-Iraq era of US foreign policy. Consistent with this, the US military presence is decreasing. Where the two candidates differ is on the timing and pace of this drawdown, not on its general direction.
By contrast, the US commitment to Afghanistan will increase, and troop levels will climb. Behind this prediction is a widely shared assessment that the trends in Afghanistan (unlike in Iraq) are negative, and that the US must strengthen its military presence there and revise its strategy if the Taleban are not to gain the upper hand.
It is also widely understood that Pakistan has become part of the problem. Pakistan's western reaches are now a sanctuary for militias and terrorists that are moving in and out of Afghanistan. Here, Senator Obama appears more willing to have the US launch unilateral military raids against terrorists should the opportunity arise.
But whoever is elected will confront difficult choices if a nuclear-armed Pakistan remains unable or unwilling to act as an American partner and meet its responsibilities in the effort against terrorism.
A third area of some consensus (and some distance from George W. Bush) is climate change. Under the next president, the US will no longer be a drag on international efforts to create a global regime that sets a ceiling on greenhouse gas emissions. One result of this likely evolution in US policy is that pressure will shift to other countries, particularly China and India, to accept some limits on their own economic behaviour.
A President McCain or Obama will take steps to improve America's image in the world. One of his first decisions will be to implement a ban on all forms of torture. Also to be expected early on is a decision to close the facility at Guantanamo Bay, where terrorism suspects have been held for years without trial.
Iran is another area where the differences - at least initially - may not be as sharp as the campaign suggests. Both candidates have stressed that an Iran with nuclear weapons would be unacceptable. The victor will almost surely endorse a new diplomatic initiative aimed at ending Iran's independent ability to enrich uranium. Less clear are the details of such an initiative, or what the US would do if it were to fail.
On other issues, such as trade, there are distinctions between the candidates. Senator McCain is a stronger advocate of free trade than Senator Obama is. But this difference may have less impact than meets the eye.
Congress plays a large role in trade policy, and the near certainty that the Democratic Party's majority in Congress will grow after the election means that protectionism will grow as well. Difficult economic times will make it hard to generate support for trade pacts, despite the current importance of export-oriented firms for the US economy.
There are real and important differences between the two candidates when it comes to how they would approach the world. But there are also more similarities than might be evident from the debates and the campaign.
Aspects of the next president's foreign policy are there to see if observers read between the lines and take as much note of what is not said as what is.
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