WASHINGTON (AFP) – After months of rising tension, the United States is gingerly exploring how to launch talks with North Korea without loosening the screws on the isolated state, experts say.

President Barack Obama has made dialogue a hallmark of his foreign policy, extending a hand to regimes no matter how odious in US eyes.

A major exception was North Korea, which since Obama took office has tested a nuclear bomb and allegedly torpedoed a ship in the deadliest inter-Korean incident in decades.

The United States has kept up the pressure, on Monday slapping sanctions against North Korean entities including its military intelligence bureau. But a growing number of US officials and analysts, even hawks, say talks have been moribund for too long.

“If you’re whacking one end of the donkey with a stick, it’s good periodically to check on the other end to see if the donkey has changed its behavior,” said Bruce Klingner of the conservative Heritage Foundation.

Secretary of State Hillary Clinton on Tuesday conferred with former President Jimmy Carter, who visited North Korea last week to secure the release of an imprisoned American teacher.

Top negotiators from China and South Korea are also visiting Washington this week to meet with senior US officials. North Korea’s leader Kim Jong-Il just paid a five-day visit to China, his regime’s main supporter.

Surprising many observers, Kim did not meet Carter, who helped broker an end to a 1994 crisis in North Korea. But the former President met with number two leader Kim Yong-Nam, who voiced support for resuming six-nation nuclear disarmament talks.

State Department spokesman Philip Crowley said North Korea must first end “provocative and belligerent behavior” and comply with a 2005 agreement reached during six-way talks, in which Pyongyang committed to ending its nuclear program in return for aid and security guarantees.

“If we see evidence that North Korea is prepared to move in that direction, then we are open to further engagement,” Crowley told reporters.

North Korea has repeatedly voiced willingness to return to the table but insisted that the United States recognize it as a nuclear power.

L. Gordon Flake, executive director of the Mansfield Foundation, said North Korea needed to moderate its stance if it truly wanted talks, as otherwise the United States feared legitimizing its claim as a nuclear power.

“The United States does need some kind of fig leaf,” said Flake, who advised Obama when he was a presidential candidate.

But few expect breakthroughs at a delicate moment in North Korea, where experts say Kim Jong-Il is preparing a power transfer to his young son Kim Jong-Un and an already dire economy has been thrown into havoc by a ham-fisted currency revaluation.

Michael Green, who served as the top Asia adviser to former President George W. Bush, expected that talks would begin within months but that the Obama administration would insist on a broad agenda.

“The consensus that’s probably emerged is that we need contact with North Korea,” said Green, now a scholar at Georgetown University and the Center for Strategic and International Studies.

“If we have a policy that is only made up of sanctions, military exercises and pressure,” Green said, “you do run some risk of pushing Pyongyang into a corner.”

“At a time of potentially profound change within North Korea, you lose some opportunities to gauge and test where things are headed,” Green said.

He added that the administration appeared determined not to accept North Korea’s demands to ease sanctions in exchange for talks.

But Green said the United States has also sidestepped calls from hawks in South Korea for a more robust response to the March sinking of the Cheonan corvette, which killed 46 sailors.

“Like Goldilocks and the Three Bears, the administration got it about right – not too hot, not too cold,” he said.