Dunford last month said that while a war with North Korea would involve "a loss of life unlike any we have experienced in our lifetimes", it was "not unimaginable". "The visit underscores US interest in further developing military-to-military relationships between the United States and China", the statement said.
McMaster, appearing on ABC's This Week, said "we're not closer to war than a week ago, but we are closer to war than we were a decade ago".
Central Intelligence Agency director Mike Pompeo offered assurances Sunday there was "nothing imminent" in the United States standoff with nuclear-armed North Korea but said he wouldn't be surprised if Pyongyang conducted another missile test.
White House officials have insisted the investigation is not created to apply additional pressure on China as it relates to North Korea despite the president's previous remarks that he would be more amenable on trade if China stopped Pyongyang's nuclear program.
Pressed on his "nothing imminent" statement, Pompeo said: "What I'm talking about is, I've heard folks talking about that we have been on the cusp of a nuclear war". "And so this is why what Kim Jong Un is doing is very, very risky".
Marine Gen. Joseph Dunford, chairman of the U.S. Joint Chiefs of Staff, reaffirmed the U.S. commitment to protect South Korea after a meeting with President Moon Jae-in, spokesman Park Su-hyun told reporters in Seoul on Monday.
Some analysts expect further escalation in the coming days as both North and South Korea celebrate the August 15 anniversary of the end of Japan's occupation of the Korean Peninsula, and the latter conducts joint military exercises with the U.S. starting August 21.
"The US military is locked and loaded every day", Mr McMaster said, repeating Mr Trump's threat. Trump has said he might be more forgiving of China's lopsided trade with the United States if it pressures North Korea more.
In response, Mr Trump said North Korea should expect "big, big trouble" if anything happened to Guam.
At a regional security conference in Manila last week, Chinese Foreign Minister Wang Yi urged his North Korean counterpart, Ri Yong Ho, to comply with United Nations prohibitions on its missile and nuclear testing.
North Korea announced on Thursday plans to fire missiles near the US Pacific territory of Guam, even though there was no indication an attack is imminent.
Pompeo said that Kim responds to "external stimulus", such as pressure from China and ultimatums from the White House, but he suggested that may be insufficient.
Pompeo said "there's nothing imminent today", in response to a question about how anxious should people be over the escalating tensions.
Pompeo said "there's nothing imminent today", in response to a question about how anxious should people be over the escalating tensions, on "Fox News Sunday". "That's the best message you can deliver to someone who's putting America at risk".