On Monday he said: "This is a real threat to the world, whether we want to talk about it or not".
In this photo taken April 26, 2017, U.S. Pacific Command Commander Adm. Harry Harris Jr. testifies on Capitol in Washington before a House Armed Services Committee hearing on North Korea.
"The United States seeks stability and the peaceful denuclearisation of the Korean peninsula", the Trump administration said.
"There is not a pretty military solution here", Cardin said. "This is a Senate-led meeting that they are getting; those four briefers will share to them the current situation in North Korea", he said.
Washington and Pyongyang have been ratcheting up pressure on each other in recent weeks, with the United States sending a aircraft carrier group and nuclear submarine to the region and North Korea attempting more missile launches in defiance of layers of U.N. sanctions. He is the third USA citizen believed to be now detained in North Korea. Trump's top national security advisers said they were "open to negotiations" with the North, though they gave no indication of when or under what circumstances. An Ohio-class guided missile submarine, the USS Michigan, docked at the South Korean naval base of Busan on Tuesday, the USA navy reported, in what was described as "a routine visit".
Trump, in the phone call with Xi, "criticized North Korea's continued belligerence and emphasized Pyongyang's actions are destabilizing the Korean Peninsula", according to a White House readout issued Monday.
All 100 USA senators have been invited to the White House Wednesday for a briefing on North Korea, but it's "not a White House briefing", presidential spokesman Sean Spicer told reporters on Monday.
"You have seen some early indications of China doing a better job enforcing existing United Nations sanctions on North Korea", the official said, adding there had also been a clear effort to communicate to North Korea in the Chinese press "that its nuclear tests, missile tests, the existence of these programs can't be tolerated".
Graham told Fox News he was impressed by Trump's resolve. He suggested last week that Mr. Trump was considering force against North Korea - perhaps without explicit congressional approval - but said Tuesday that the Senate meeting will be more broadly focused. Tillerson is chairing a U.N. Security Council meeting Friday created to get nations to enforce existing penalties on North Korea and weigh new ones. It vowed victory in a "death-defying struggle against the US imperialists".
Abe also said he and Trump agreed that a larger role in dealing with Pyongyang should be played by China.
So far, North Korea has remained defiant.
"Having dealt with the North Korean nuclear issues for more than 20 years, it's extremely hard for anyone to come up with an entirely new yet sound approach at this point", an official at Seoul's Foreign Ministry said on customary condition of anonymity. In Berlin Wednesday, Foreign Minister Wang Yi said North Korea must suspend its nuclear activities, but "on the other side, the large-scale military maneuvers in Korean waters should be halted".
The deployment of Terminal High-Altitude Area Defense (Thaad) system in South Korea was aimed, he argued, at bringing North Korean leader Kim Jong-un "to his senses, not to his knees". He said China will take "necessary measures to defend our own interests".