While the conflict with Iran continues to gather more media attention, today’s biggest news may have come from South Korea, whose free-trade agreement with the U.S. is coming into force. The Wall Street Journal calls it the largest free trade pact America has signed since NAFTA. The agreement will see 80 percent of existing tariffs between the two countries eliminated this week, with a further 15 percent to follow by 2017.This agreement is about more than just economics. Rising tensions off China’s coast have made Korea strategically important as never before, so the U.S. is now using the power of the market to deepen ties with a geopolitically important country.Via Meadia thinks this is a smart move all around. Strengthening ties, both economic and political, with China’s neighbors is a key piece of American strategy in Asia. A wide-ranging free trade agreement like this one is certainly an effective way to accomplish this. It should also play well at home; with NAFTA, critics feared the effects of a trade agreement with a low-wage country like Mexico. South Korea, at a much higher level of development, doesn’t present this problem.But we should remember that China can play this game too, especially as its economy grows. For China’s neighbors, trade with China is often a larger factor than trade with America, and they will find similar offers from Beijing hard to resist. Fortunately, trade is not a zero-sum game; the U.S. will benefit from deeper trade ties and freer trade across Asia. But American policymakers shouldn’t forget that China, too, will be deploying trade strategies to advance a political and strategic agenda.