Secretary of State Rex Tillerson warned Tuesday that if North Korea does not choose to negotiate on giving up its nuclear weapons that pose a growing threat to the United States it could trigger a military response.

After a meeting of U.S. allies on how to beef up the sanctions pressure, Tillerson stressed that the Trump administration seeks a diplomatic resolution in the nuclear standoff, but he said the North has yet to show itself to be a “credible negotiating partner.” He said U.S.-North Korea talks would require a “sustained cessation” of threatening behavior.

Tillerson declined to comment on whether the White House is considering limited military action against Pyongyang, in response to reports that some in the Trump administration advocate military action to give the North a “bloody nose.”

“We all need to be very sober and clear-eyed about the current situation,” Tillerson said when he was asked whether Americans should be concerned about the possibility of a war. He said North Korea has continued to make significant advances in its nuclear weapons through the thermonuclear test and progress in its intercontinental missile systems.

“We have to recognize that the threat is growing and that if North Korea does not choose the pathway of engagement, discussion, negotiation then they themselves will trigger an option,” he said.

His uncompromising message came after a gathering in Vancouver of 20 nations that were on America’s side during the Korean War, where there was skepticism among the allies over North Korea’s sincerity in its recent diplomatic opening with the U.S.-allied South. The meeting convened days after a mistaken missile alert caused panic on Hawaii, a stark reminder of the fears of conflict with the North.

Despite Washington’s tough stance and determination to keep up the pressure on North Korea, President Donald Trump has signaled openness to talks with the North under the right circumstances. After months of insults and blood-curdling threats traded with North Korean leader Kim Jong Un, Trump suggested in an interview last week that the two leaders could have a positive relationship.

Tillerson declined to say Tuesday whether Trump has spoken directly to Kim.

“I don’t think it’s useful to comment” he said. “We are at a very tenuous stage in terms of how far North Korea has taken their program and what we can do to convince them to take an alternative path. And so when we get into who’s talking to who and what was said, if we want that to be made know or made public we will announce it.”

South Korean Foreign Minister Kang Kyung-wha said its talks with North Korea, leading to the North’s participation in next month’s Olympics being hosted by the South, are a “significant first step toward restoring inter-Korean relations.”

But she conceded that despite the overtures, North Korea has yet to show any intention to fulfill its obligations on denuclearization of the Korean Peninsula.

Japanese Foreign Minister Taro Kono was blunter. He said the North “wants to buy some time to continue their nuclear and missile programs.”

The meeting was attended by foreign ministers and senior diplomats of nations that sent troops or humanitarian aid to the U.N. Command that supported South Korea in the fight against the communist North and its allies during the 1950-53 Korean War. It’s a diverse gathering of mostly European and Asian nations, as well as Australia, New Zealand and Colombia.

The delegates were briefed Monday night by Defense Secretary Jim Mattis. A senior State Department official described that as a chance to demonstrate that the U.S. has an integrated strategy and to raise confidence that it definitely prefers a diplomatic solution over resorting to military action. The official was not authorized to speak publicly about the briefing and requested anonymity.

The gathering, co-hosted by Canada and the U.S., had few concrete outcomes and was principally intended as a show of solidarity. But it alienated China and Russia, which fought on the communist side in the war and were not invited. U.S. officials say those two nations, which are the North’s main economic and diplomatic partners, will be briefed afterward.

Beijing and Moscow have supported U.N. Security Council resolutions to restrict export revenue for North Korean nuclear and missile development. They are more forward-leaning than Washington in their calls for negotiations with Kim’s government. The sanctions also limit imports by North Korea of oil and petroleum products, most of which are supplied by China.

Tillerson said all nations must work together to improve maritime interdiction operations and stop illicit ship-to-ship transfers that violate U.N. sanctions. He said the allies did not seek to interfere with “legitimate maritime activities.” He said most interdictions to date have taken place in ports and have not required military action.

The latest U.N. Security Council resolution, adopted in December in response to an ICBM test, calls on member states to impound vessels in their ports if there are reasonable grounds to suspect illicit trade with North Korea. It authorizes interdictions in a member state’s territorial waters.

(AP)