* Calls for negotiations but Washington unmoved
* Evidence North Korea wants to talk uncertain
* China seen part of problem, not solution
* Hu Jintao trip to U.S. seen as opportunity (Adds quotes, China details)
By Paul Eckert
WASHINGTON, Nov 23 (Reuters) - North Korea's artillery attack on U.S. ally South Korea poses the second test in three days of Washington's vow that it will not reward what it deems bad behavior with diplomatic gestures, and underscores that U.S. options are limited without serious help from China.
One of North Korea's heaviest attacks on the South since the Korean War ended in 1953 followed revelations at the weekend of a uranium enrichment facility -- a second source of atomic bomb material in Pyongyang's nuclear program.[ID:nL3E6MN0SQ]
The attack prompted China to call for a return to six-party aid-for-disarmament talks, a view echoed by U.S. critics of the Obama administration's policy of "strategic patience" -- sanctions combined with a willingness to talk with the North only if Pyongyang shows seriousness about disarmament.
"We've got to get back to negotiations with North Korea. But I notice that that's being ruled out at least for the moment by the White House," Donald Gregg, former U.S. ambassador to South Korea, told ABC's "Good Morning America".
The White House, which until now has not wanted to be goaded into resumption of the talks, limited its reaction to condemning the attack, calling on North Korea to halt its belligerent actions and reaffirming its commitment to defend South Korea.
U.S. WON'T BE FORCED
Victor Cha, who dealt with North Korea in the former President George W. Bush administration's National Security Council, agreed with that stance, saying it would be premature for Washington to seek negotiations with North Korea now.
"This assumes they (the North Koreans) want to talk, but I'm not at all certain that they want to talk at all," said Cha, now at Georgetown University and the Center for Strategic and International Studies think tank.
In contrast with past flare-ups in which North Korea provoked crises to draw Washington or Seoul back to the negotiating table, this time it appears Pyongyang is "basically bent on strengthening their deterrent and showing everybody else that they are not an unstable regime as they go through this leadership transition," he added.
North Korea's ailing leader Kim Jong-il is trying to make his untested youngest son his heir apparent.
U.S. President Barack Obama came to office in January 2009 offering talks with North Korea, but changed tack in the face of missile launches and a nuclear test by North Korea last year. Tensions increased with the torpedoing of South Korea's Cheonan navy ship in March. Seoul and its allies blamed the sinking on Pyongyang, but North Korea has said it was not to blame.
Washington's refusal to be forced to negotiate or to hold talks for talks' sake "hasn't changed and I don't think this incident will change that at all" said Charles Pritchard, a former U.S. diplomat and president of the Korea Economic Institute.
CAN CHINA BE MOVED?
Help from China, Pyongyang's closest ally, is crucial for Washington as it seeks to reduce the danger of nuclear weapons in the hands of an isolated and irascible state.
Cha said the key U.S. task now was "getting the Chinese to say the right things at the very beginning publicly" -- that the uranium program violates U.N. Security Council resolutions and the artillery attack runs afoul of the Korean War truce.
China has yet to offer such condemnation and past evidence suggests Beijing will continue to resist pressure from Washington and Seoul to get tough.
Beijing, responding to the artillery barrage in the same way it did to the more deadly sinking of the South Korean warship, avoided taking sides, calling on both Koreas to "do more to contribute to peace."
On Tuesday, China's state media announced a new trade pact was signed by the DPRK-China Intergovernmental Committee for Cooperation in Economy, Trade, Science and Technology in Pyongyang.
"That the Chinese continue to abet the North Korean's tactics should also make us think long and hard about the sort of partner/competitor we face with China," said Korea expert Bruce Klingner of the Heritage Foundation in Washington.
Chinese aid and investment has helped North Korea weather repeated rounds of U.N. sanctions imposed over nuclear and missile tests since 2006.
Washington has had difficult ties with Beijing throughput 2010 as the two have clashed over issues such as trade and currency, human rights and climate change.
But some analysts hope that China might be more helpful on North Korea in coming months to ensure a smooth state visit to the United States by Chinese President Hu Jintao in January.
Cha said the North Korea conundrum remains exactly as he faced it in the Bush era.
"North Korea was described to me as the land of lousy options. You're never choosing between good and bad options. You're choosing between bad, worse and the worst," he said. (Additional reporting by Arshad Mohammed and David Morgan; Editing by Frances Kerry)
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