USA is interested in dialogue with North Korea; lines of communication are open: Secretary of State Rex Tillerson

The United States is probing North Korea to see whether it is interested in dialogue and has multiple direct channels of communication with Pyongyang, U.S. Secretary of State Rex Tillerson said on Saturday.

"We are probing, so stay tuned," Tillerson told a small group of reporters during a trip to China. "We ask: Would you like to talk? We have lines of communications to Pyongyang. We're not in a dark situation."

Earlier, Tillerson held top-level talks in China on Saturday as the United States looks to tighten an economic squeeze aimed at persuading North Korea to retreat from its nuclear arms and missile programs.

The United States sees China as critical to averting a military confrontation with Pyongyang, which is fast advancing toward its goal of developing a nuclear-tipped missile capable of reaching the United States.

U.S. officials say Beijing appears increasingly willing to cut ties to North Korea's economy by adopting U.N. sanctions, after long accounting for some 90 percent of its neighbor's foreign trade.

But to succeed in reaching any kind of diplomatic solution, Tillerson would need to overcome some basic U.S. assumptions about North Korea and China.

The first would be getting North Korean leader Kim Jong Un to view nuclear weapons as a liability, not a strength. The U.S. intelligence community does not believe Kim is likely to willingly give up his weapons program.

"(Tillerson's) working against the unified view of our intelligence agencies, which say there's no amount of pressure that can be put on them to stop," Senator Bob Corker told a Senate hearing on Thursday.

Kim, Corker said, saw nuclear-tipped intercontinental ballistic missiles as "his ticket to survival".

The second big challenge for Tillerson would be getting China to impose economic sanctions on North Korea so harsh that Kim might question his future if they persisted.

U.S. officials, speaking on condition of anonymity, say they believe China's priority is stability on the Korean peninsula, since a political collapse would almost certainly push destabilizing waves of refugees into northeastern China.

China says it will strictly and fully enforce U.N. resolutions against North Korea and its Commerce Ministry on Thursday said North Korean firms in China and joint ventures in China and overseas would be shut down by January, in line with the latest U.N. resolution.

But the latest sanctions need time before they begin to bite, the official China Daily cautioned in an editorial on Friday.

U.S. President Donald Trump, who is due to visit China in November, has called for it to do more on North Korea and has promised to take steps to rebalance a trade relationship that his administration says puts U.S. businesses at a disadvantage.

Tillerson, whose arrival in Beijing was delayed due to mechanical problems with his aircraft, told Chinese Foreign Minister Wang Yi that Trump was looking forward to his China visit.

Tillerson also held talks with President Xi Jinping, and China's top diplomat State Councillor Yang Jiechi, who outranks the foreign minister.

There was no mention of North Korea in any of the remarks in front of reporters, nor in the Chinese government's account of the meeting with Xi, which focused on Sino-U.S. cooperation.

"The correct direction must be upheld in developing China-U.S. relations. Both countries' common interests far outweigh our disputes, and cooperation is the only correct choice for both sides," China's Foreign Ministry cited Xi as saying.

The U.S. State Department did not suggest any major announcements would be made on Tillerson's trip but the China Daily said it needed to be more than a "routine show of mutual goodwill" ahead of Trump's visit.

"The guest and his hosts must ... straighten at least one thing out - what each can expect from the other to ensure the situation on the Korean peninsula does not deteriorate and spiral out of control," it said.

UNACCEPTABLE OPTIONS

Senator John McCain, who heads the Senate Armed Services Committee, said this week he was sceptical.

"The ideal, we all know, is China. China has not done anything for the last three presidents. I'm not sure that they're going to do anything with this one," McCain told a security conference in Washington hosted by the Institute for the Study of War.

McCain has repeatedly warned that the United States, which neither wants to live with a nuclear-armed North Korea nor go to war with it, may be faced with "unacceptable options".

U.S. officials have declined to discuss operational plans, but acknowledge that no existing plan for a preemptive strike could promise to prevent a brutal counterattack by North Korea, which has thousands of artillery pieces and rockets trained on Seoul.

White House National Security Adviser H.R. McMaster said on Monday that even military options short of a preventative strike, such as a naval blockade meant to enforce sanctions, carried risks of military escalation.

Tillerson has in the past expressed hope for dialogue with North Korea. U.S. diplomats have also sought to assure Pyongyang that Washington is not seeking to oust Kim, even as Trump and Kim exchange insults and threats of war.

"We are not seeking regime change or collapse," State Department Assistant Secretary Susan Thornton, who is travelling with Tillerson, told a Senate hearing on Thursday.

Thornton's remarks were welcomed in Beijing, which is calling for a peaceful solution to the crisis.

Chinese Foreign Ministry spokesman Lu Kang said the United States had issued many "positive signals" that the North Korean nuclear issue should be resolved via talks.

Still, it is unclear how and when negotiations with Pyongyang might be possible.

McMaster said there was no set list of preconditions for talks but added Pyongyang's capabilities had advanced too far to simply freeze its program in return for concessions.

He cited academic reports about actions North Korea could take to suggest it was serious about talks, such as allowing International Atomic Energy Agency inspectors access to key sites and stating that Pyongyang was willing to denuclearize.

"What we want to see is negotiations that begin under fundamentally different conditions" than in the past, McMaster said.