HANOI, Vietnam (AP) — Defence Secretary Mark Esper is returning from Asia with the US still facing a trio of troubles on the Korean peninsula that pose risks to the national security of the US and one of its most important alliances in the region.

The toughest of these problems, and arguably the most consequential, is North Korea’s refusal to restart negotiations with Washington on eliminating its nuclear weapons.

Esper, who was returning yesterday to Washington, has no direct role in nuclear diplomacy, but he had hoped that his decision to postpone a military flying exercise with South Korea — which North Korea had criticised as provocative —would help nudge the North back to the negotiating table.

In announcing the postponement in the Thai capital last weekend, Esper called it an “act of goodwill” that would not degrade the combat readiness of US and South Korean air forces. But the North quickly rejected the gesture.

A senior North Korean official, Kim Yong Chol, said the US must scrap the military drill completely and abandon its hostility against his country if it wants to see the resumption of the nuclear negotiations.

Esper told reporters yesterday in Vietnam’s capital, Hanoi, that he was disappointed by the North’s negative response.

“But I don’t regret trying to take the high road, if you will, and keep the door open for peace and diplomacy,” he said.

At stake is the possibility of a return to the level of tension that not long ago pushed both sides toward war.

Esper himself asserted last week that when he became Army secretary in late 2017, “we were on the path to war; it was very clear to me because the Army was making preparations”.

Bruce Bennett, a North Korea analyst at the RAND Corp, a federally funded think-tank, sees a dangerous diplomatic disconnect.

“North Korea has been unwilling to explain what an end to ‘US hostile policy’ means other than to say that the US must no longer treat North Korea as an enemy,” Bennett said in an e-mail exchange this week. “The dozens of US statements saying that the United States does not seek to destroy the regime have not met this North Korean requirement.”

Bennett thinks it’s possible that the North will be satisfied with nothing less than a withdrawal of all 28,500 American troops from South Korea and a dissolution of the US-South Korean defence alliance that emerged from the 1950-53 Korean War.

North Korea has demanded that the US come up by the end of this year with a mutually acceptable approach to resuming negotiations on eliminating the North’s nuclear weapons and the infrastructure that supports it.

“They may move in a different direction” at that point, Esper said Thursday. “So I think we have to keep pressing forward. It’s too important not to keep trying.”

Complicating that effort is a new fissure between Seoul and Washington. The Trump Administration is demanding a five-fold increase in the amount Seoul pays to keep US troops in the country — up from just under $1 billion this year.

Esper is not leading those negotiations, but he said in Seoul last week that South Korea is wealthy enough to pay more. Shortly after that, the talks led by the State Department broke down. Seoul’s view is that Washington is making an unreasonable demand for billions more in payments.

Esper dismissed reports that the US is threatening a partial troop withdrawal if Seoul does not meet Washington’s payment demands.

“We’re not threatening allies over this,” he said.

The third rift in relations that Esper encountered in Seoul is a standoff between South Korea and Japan — both US defence treaty allies. Seoul says it will withdraw this week from an intelligence-sharing agreement with Tokyo, despite US urgings that they settle their differences.

In Seoul, Esper told his Japanese and South Korean counterparts privately and in public that their dispute was only benefiting North Korea and China. But his words seemed to make no difference.