It's an ill wind that blows no good, the old saying goes. Which brings us to the earthquake in Japan -- and China's leaders in Beijing.

Beijing surely realizes that its own standing -- in the region and in the world -- increases in the wake of Japan's devastation. That makes the US-Japan alliance more critical than ever to managing China's rise and the balance of power in Asia.

Japan will inevitably turn inward in its struggle to overcome the disaster. Its leaders must focus first on rescue and relief operations, then the daunting task of repairing and replacing so much ruined infrastructure.

Tokyo will likely be too busy to respond to events even on its near horizon. It will resist requests to devote humanitarian, diplomatic or military assets to international missions far from its shores.

For some time to come, then, China can act more freely in the region without much fear of provoking a Japanese response. Yes, Tokyo is still likely to respond sharply to any Chinese encroachment on the disputed Senkaku/Diaoyutai Islands -- but it may be too preoccupied to respond to Chinese assertiveness elsewhere, such as disputed boundaries in the East China Sea.

Meanwhile, resources for Japanese security and outreach efforts will now be much more constrained. The Japanese Self-Defense Forces must devote resources to rescue operations that would normally go to training and maintenance. And future defense outlays may be cut even more than the 3 percent trims for 2011-2015 that Japan announced earlier this year.

Japan's foreign aid is also likely to drop. That's bad news for a number of key Asian players, including Indonesia and India, two of the largest recipients of Japanese assistance. The lack of funds from Tokyo will leave more of the Asian field to the Chinese.

But wait, you ask -- isn't Beijing showing a new friendliness by immediately dispatching assistance? Perhaps -- but the amount seems calibrated to keep the impact mainly symbolic: Surely the world's No. 2 economy can do better than a paltry few million dollars . . .

But then, Chinese industry may not benefit as much as you'd expect from Japan's bad fortune. Yes, the island nation may be seriously hurt by the loss of factories, supplies and transportation infrastructure. But the People's Republic isn't well-suited to capture Japan's auto-export business, to take but one example.

Moreover, China-based production of consumer goods depends heavily on inputs from Japan. Higher building-materials prices from the reconstruction effort will push Chinese property prices up even more.

How will the earthquake affect Japan's government? Prime Minister Naoto Kan's political life was hanging by a thread before the earthquake; a surprise display of strong crisis-management skills might help him and his embattled Democratic Party of Japan, both of which were suffering from plummeting public approval ratings. At a minimum, the crisis may induce opposition politicians to rally 'round the flag, breaking the current stalemate on the budget and other key legislation.

But Japanese leaders have not been known for bold, decisive leadership in recent decades; a poor showing by Kan could accelerate his departure from office. Since his expected successor, Foreign Minister Seiji Maehara, recently resigned over a political funding scandal, the country could face the added burden of a period of weak and/or constantly changing leadership.

The role of the US military in Japan may also be affected. There's been considerable public resistance on Okinawa to a planned realignment of the US Marine Corps on the island, with critics claiming the Americans serve no purpose. This view may change, as US military assets, including units from Okinawa, have responded to the catastrophe.

One thing is certain: Japan needs to cooperate with the US in the Pacific more than ever.

Bruce Klingner is a senior research fellow for Northeast Asia in the Heritage Foundation's Asian Studies Center.