As the world struggles with the ongoing crisis in Syria, a potentially even greater clash has been moving in slow motion between the world’s number two and three economies. It has the potential to draw the United States into a conflict that would dwarf what the world confronts today in the Middle East.

In East Asia for the past several years, the Senkaku/Diaoyu islands have been a source of tension between China and Japan. Washington has made lukewarm statements of support for Tokyo. However, now is the time to move past any ambiguity. To remain a strong power in Asia, the United States must be absolutely clear that it will support Japan militarily against any armed Chinese aggression over the Senkaku/Diaoyu islands.

For a year now, we have seen a dangerous game being played out in East Asia. Last September, the Japanese government purchased three of the disputed islands from their private owners, drawing censure from Beijing and thus creating new tensions in the Sino-Japanese relationship. If there is an armed clash over the Senkakus, America will have to make an ominous choice: abandon Japan or fight China. The question is how to avoid such a grave situation from ever coming to pass.

For months, President Obama has been urging China and Japan to “deescalate,” and seek a diplomatic solution. The president’s light touch has been backed up by statements from various U.S. officials that the islands fall within the scope of the treaty with Japan.

But the softly-softly approach hasn’t worked. Beijing is still aggressive; it has started calling the islands a ‘core interest,’ which is a phrase usually reserved for issues like Taiwan. And Japan is increasingly nervous.

In fact, by allowing Beijing to entertain the notion that America may not get involved, Obama’s approach has encouraged armed aggression by China. Just last week, a senior PLA officer warned the U.S. against supporting Japan. China's defense ministry reported their American interlocutor (Under Secretary of Defense for Policy James Miller) responding that the U.S. didn't take sides, and was urging restraint. Beijing is questioning Washington's resolve—it's fertile ground for miscalculation leading to war.

If that were to happen, the costs to America’s alliance and partner network in Asia would be huge. Abandoning Japan would mean relinquishing the alliance, and likely also America’s whole position in Asia. Talk of an Asia “pivot” or “rebalance”—already being challenged in many circles—would clearly be done for.

The danger is that China doesn’t recognize that, so Obama needs a new approach. One suggestion is that President Obama could make a statement along these lines, removing any hint of ambiguity:

The United States encourages Japan and China to reach a peaceful, mutually acceptable resolution to the dispute over the sovereignty of the Senkaku/Diaoyu Islands. We urge each side to show restraint in defending their claims, and flexibility in reaching a settlement. Until a settlement is reached, and as long as Japan undertakes this process in good faith, the United States will regard any aggression by Chinese forces towards Japanese forces over the issue of the possession of the islands as falling within the provision of Article V of the Treaty of Mutual Cooperation and Security between the United States and Japan. And we would not hesitate to fulfill our treaty obligations by all necessary means.

There are three concerns, which might weigh on the mind of a president thinking of making such a statement.

First, the islands themselves are small, barren, and almost worthless. Why risk war with China and possibly the potential of a nuclear exchange over something so unimportant?

But Tokyo sees things differently; it considers them part of Japan. And whether the islands are intrinsically valuable or not, they are now a symbol of Japanese (and Chinese) pride, and of Tokyo’s capacity to protect its interests in the face of a rising China.

More importantly, the U.S. isn’t worried about the islands; it’s worried about two principles. The first is that America will support Japan when it faces pressure—particularly from China. The second is that Washington opposes the use of armed force to settle disputes. What’s at stake for the U.S. in supporting these principles is its position as a major power in Asia.

Second, the White House could be avoiding a clear declaration because it might inflame the situation. And it almost certainly would. The period of time immediately after this kind of statement would be tense.

But how serious is this risk, compared to the risk that ambiguity from Washington would encourage China to push too far and create a crisis? Even strategists are prone to see what we want to see, and China wants to see a Washington that is disinclined to come to Japan’s aid.

Although the declaration would bring a sharp response from Beijing, a China that is expecting a U.S. military response would be more hesitant to use force than one that wasn’t sure.

If China already believes the U.S. is committed over the islands, as most supporters of Obama’s tactful silence assume, the blow-back should be more bark than bite.

China will be genuinely angry if American support for Japan comes as a surprise. But that would mean that chances of a Chinese miscalculation are high, so the declaration would also help to mitigate a very serious genuine risk. In fact the more the declaration above would enrage Beijing, the more important it is that President Obama gives it.

Third, there’s the concern that the U.S. would have to take sides over the murky legal and diplomatic elements of the dispute. That might actually hinder the resolution of the crisis. But as the formulation above shows, it’s perfectly possible for the administration to have a two-part message; America requires Japan to work towards a peaceful solution, but the alliance holds until it is found. As long as the message contains both parts, it will also stop Japan using U.S. support as cover to avoid settling the issue.

Ultimately, of course, the main reason it is so important for President Obama to be absolutely clear in his support for Japan, is that the tensions aren’t about Japan and China at all. They are about America and China. The Islands are insignificant, and Sino-Japanese enmity is nothing new. What is new is China’s sense that it can begin to flex its muscles in Asia; it can push around America’s most important and most powerful ally. That’s why if America wants a role in Asia, it must support Japan on the Senkakus.

Harry White is an analyst at the Australian Strategic Policy Institute; these views are his own. Follow him on Twitter: @HarryEWWhite