All 100 US Senators have been told that the US is “prepared to defend” itself in the face of any threat from North Korea at a special briefing in Washington.
The classified briefing heard that the Trump administration is seeking a peaceful denuclearisation of the Korean peninsula.
Washington hopes to pressure Pyongyang into dismantling its nuclear and ballistic missile programmes through tightened sanctions and bring it back to the "path of dialogue," according to an administration statement after the briefing.
However, the statement warned that the US was "prepared to defend ourselves and our allies".
It added: "We are engaging responsible members of the international community to increase pressure on [North Korea] in order to convince the regime to de-escalate and return to the path of dialogue."
South Korea and the United States have agreed on "swift punitive measures" against North Korea in the event of provocation.
Special senators briefing
US Secretary of State Rex Tillerson, Defence Secretary Jim Mattis, US General Joe Dunford and National Intelligence Director Dan Coats staged the briefing for the senators at a building close to the White House.
A similar briefing will be held for members of Congress in the Capitol.
Although highly unusual, it does not necessarily signal an imminent security crisis despite increased tensions on the Korean Peninsula.
Nuclear threat?
Concerns have been raised over whether North Korea is developing a nuclear-armed missile that could strike the US.
Earlier on Wednesday, Admiral Harry Harris, who heads the Pacific Command, said the US wants to bring North Korean leader Kim Jong-Un to "his senses" and welcomed efforts by China to defuse tensions.
He said: "In confronting the reckless North Korean regime, it's critical that we're guided by a strong sense of resolve, both privately and publicly, both diplomatically and militarily.
"All options are on the table. We want to bring Kim Jong-Un to his senses, not to his knees."
Anti-missile system
US forces have begun deploying an anti-missile system in South Korea that has triggered anger from China.
The Terminal High Altitude Area Defence (THAAD) system is being set up on a former golf course in Seongju amid protests that have seen demonstrators clash with police.
It is designed to intercept and destroy short and medium-range ballistic missiles.
North Korea has carried out a series of missile launches in recent months and the US has responded by deploying an aircraft carrier group to the region.
