WASHINGTON — Much of the United States' ground combat might is tied up in Iraq and Afghanistan, and the United States is reducing its infantry forces in South Korea.

But American air and sea power in east Asia, a key to almost any imaginable military conflict with North Korea, has grown in numbers and reach.

So on balance it appears the United States has sufficient forces for the more likely military missions to be required in a Korea crisis — perhaps some form of sea and air blockade, officials and analysts say.

If North Korea lashed out by launching a surprise attack on South Korea, the United States would face hard decisions on multiple war fronts. Soldiers and Marines getting ready to rotate into Iraq would have to be diverted to Korea, requiring the troops in Iraq to stay much longer than planned.

These issues arise as the U.N. Security Council considers imposing tougher sanctions on North Korea in response to its announced nuclear test.

Rep. Ike Skelton, D-Mo., a close observer of military issues, said in an interview Tuesday that he worries that should a major military crisis erupt in North Korea, the Army and Marines would be over-stretched.

Skelton said the Army has only two fully ready combat brigades available — one in Germany, the other in Kuwait. The rest are either in Iraq or Afghanistan, are getting ready to deploy there, or have just returned.

The U.S. military has about 140,000 troops in Iraq and about 20,000 in Afghanistan, mainly soldiers and Marines.

One Army combat brigade is based in South Korea as part of a U.S. force numbering 28,000. That force has been pared down from 32,500 over the past few years and is scheduled to drop to 25,000 by 2008.

There are about 50,000 U.S. troops in Japan; of those, about 8,000 Marines are scheduled to move from Okinawa to Guam.

Michael Green, senior adviser at the Center for Strategic and International Studies, a private research group, said Tuesday that short of a total collapse of North Korea, the U.S. military has what it needs to handle the problem.

"The South Korean ground forces are strong enough to handle and deter a North Korean attack on the ground," said Green, who was senior director for Asia on President Bush's National Security Council. "What they need is help with air forces and naval forces, and that is not what we're using in Iraq right now."

He sees no shortage of U.S. air and naval power.

Skelton agrees that "we're in pretty good shape" in terms of air and naval forces available for Korean duty. He added that he does not see an immediate need to send more U.S. ground troops to South Korea.