President Lee Myung-bak and his U.S. counterpart Barack Obama said during their summit Thursday that the Seoul-Washington alliance is the "primary axis of security" for South Korea and the "foundation" of security in the Pacific for the U.S. The two leaders also vowed to strengthen the alliance to promote peace and prosperity, developing it into a "multi-dimensional strategic alliance" with greater cooperation on terrorism, the proliferation of weapons of mass destruction and the global economic crisis. The two countries have expanded their focus from politics and military affairs to the economic sphere, and beyond the Korean Peninsula to the international stage. As seen during Russian Prime Minister Vladimir Putin's visit to China, Moscow-Beijing relations are moving toward greater economic and military cooperation, making it increasingly important for Washington to strengthen its alliances in the region. The U.S. and South Korea have recently started increasing contact with North Korea and looking for ways to restart talks with Pyongyang. But after the summit Lee said he would stick to his "principled approach to North Korea based on strictly realistic views." Obama said North Korea could not be an exception to the wave of democratic uprisings around the world and warned it would only deepen its isolation should it continue to violate international regulations. As long as North Korea continues to threaten the international community with its nuclear weapons, Seoul and Washington have sent a clear message that they will offer no help whatsoever. Obama said Lee's visit signifies the rise of South Korea as a "global partner of the U.S.," and went out of his way during this meeting to charm Lee. But Seoul must remember that such warmth needs to be reciprocated. The U.S. State Department has called on Korea to play a bigger role in the international community, and such requests have increased since the earthquake in Japan in March. At the same time, Seoul must make sure it does not bite off more than it can chew. As Seoul-Washington relations deepen, it must be sure to let China and other neighboring countries know that it intends to pursue a balanced course.