I've read a number of commentaries regarding the absence of foreign policy remarks in President Obama's State of the Union message. Perhaps not directly, but indirectly all the emphasis on economic growth in the United States is proximate to the foreign policy strategy of the country.
Some time in the distant past, the New York Times conducted a poll (this is from memory, so no link) which posited questions that, simply put, asked about the public interest in national as opposed to international as a way of judging the emphasis that should be put - at the time - on network news programming. The results were surprising inasmuch as when national affairs, and specifically economic matters, were put in the context of international effect - job losses to Mexico, drops in industrial production to China and the like. The responses clearly showed that public interest in international matters increased when put in a national economic context.
Consequently, for political scientists to bemoan the strong emphasis on national economic matters is misplaced. First, the US public is clearly focused on the economic state of the union. They are not interested in and would not take kindly to the President giving more that short shrift to mentioning a US foreign policy agenda. Welcome, ladies and gentlemen academics, to politics.
More than that, however, is the fundamental fact that the US must get its economy in order if its foreign policy goals are to succeed. Economic matters - together with the wars in Afghanistan and Iraq - make it difficult to deal with Russian expansionism through support for Poland and the Baltics, finding a non-military solution on the Iranian nuclear issue and especially working on a Middle East settlement. The latter has suffered in particular since US policy, which had promised to put pressure on the Israeli government to stop illegal settlement construction (West Bank settlements are a violation of international law), has clearly been dropped from the agenda.
So, economic issues in the US directly affect its foreign policy choices. The linkage is abundantly clear and the State of the Union had the right emphasis.