Various opinion polls have shown that US voters in this year's presidential elections clearly place economic concerns ahead of foreign policy.

However, most key issues of the race are related to foreign policy, such as Iraq, national security and immigration, which in fact tie-in with the economy in many ways.

As the presidential contest becomes more intense, a number of foreign policy issues are now under spotlight.

]The February 26 debate featuring Democratic presidential hopefuls Sen. Hillary Clinton of New York and Sen. Barack Obama of Illinois in Cleveland, Ohio, covered a fair amount of foreign policy issues.

US Democratic presidential candidates Senator Hillary Clinton (D-NY) and Senator Barack Obama (D-IL) square off in the last debate before the Ohio primary in Cleveland, Ohio, February 26, 2008. (Xinhua/Reuters Photo)

Iraq, Afghanistan, the North American Free Trade Agreement (NAFTA) and Russia along with other foreign affairs topics accounted for about half of the debate.

Meanwhile, Sen. John McCain of Arizona, the presumptive Republican presidential nominee, is building his policy platform largely on national security, which he hopes to have an edge over his Democratic opponent in the general election.