The chief U.S. negotiator on North Korean nuclear issues said in Tokyo on Thursday that Washington will not impose a deadline on Pyongyang to return to the six-party talks.
However, U.S. Assistant Secretary of State Christopher Hill did not rule out the possibility of the U.S. bringing North Korea's nuclear agenda to the United Nations Security Council.
"Obviously there are a number of options," Hill told reporters after meeting with Vice Foreign Minister Shotaro Yachi. "I don't want to give artificial deadlines at this point."
The U.S., Japan, China, Russia and South Korea have increased pressure on North Korea to return to the six-way talks since Pyongyang declared in February it has nuclear weapons and would continue to boycott the talks.
Hill said he and Yachi discussed recent news reports that North Korea could be preparing for a nuclear weapons test in the near future. He did not elaborate.