“It takes a combined message there if we’re going to get effective movement out of the regime in North Korea. I think the president’s made it clear he prefers a diplomatic solution,” Mr. Tillerson said, standing next to Mr. Trump. “What the president’s doing is trying to support our efforts by ensuring North Korea understands what the stakes are.”
Still, even as Mr. Trump seemed to be slightly lowering the temperature with North Korea, he opened a new front by volunteering that he was contemplating the use of force in Venezuela. The government of President Nicolás Maduro of Venezuela has moved to shut down the opposition-controlled Parliament after a fraud-plagued referendum amid a spiraling economic crisis.
“Venezuela is not very far away and the people are suffering and they’re dying,” Mr. Trump said. “We have many options for Venezuela, including a possible military option if necessary.”
Just a day earlier, Mr. Maduro told delegates in Caracas he wanted to meet with Mr. Trump, possibly at the annual United Nations General Assembly in New York next month.
“Mr. Donald Trump, here is my hand,” Mr. Maduro said on Thursday. The Trump administration has called Mr. Maduro a dictator.
The president’s repeated threats against North Korea, starting with his “fire and fury” warning earlier in the week, have fueled deep anxiety in Asia and elsewhere in the world.
Australia’s prime minister, Malcolm Turnbull, said, “We stand shoulder-to-shoulder with the United States,” but his New Zealand counterpart, Bill English, hedged, saying his country would consider its options “on its merits.”
In Germany, Chancellor Angela Merkel expressed disapproval of Mr. Trump’s approach. “I consider an escalation of rhetoric the wrong answer,” she said, adding, “I do not see a military solution to this conflict.”
China, the key player in the region, offered a typical statement pleading for restraint and dialogue, asking that all parties “speak and act with caution and do more things that are conducive to de-escalating the tense situation and enhancing mutual trust among parties, rather than relapse into the old path of showing assertiveness and escalating tensions,” as the Foreign Ministry put it in a statement.
Global Times, a stridently nationalistic state-run tabloid in Beijing, published an editorial calling on Chinese leaders to make clear that they would not stand behind North Korea if it waged an attack against the United States and the Americans retaliated — but would oppose unprovoked American aggression.
“China should also make clear that if North Korea launches missiles that threaten U.S. soil first and the U.S. retaliates, China will stay neutral,” the editorial said. “If the U.S. and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so.”
Mr. Trump started the morning with a Twitter message saying the American military was “locked and loaded” for conflict “should North Korea act unwisely.” To reinforce the point, the president later shared a post from the United States Pacific Command stating that it was standing by for orders, should the need arise. “#USAF B-1B Lancer #bombers on Guam stand ready to fulfill USFK’s #FightTonight mission if called upon to do so,” the original tweet said.
The president followed up in the afternoon by telling reporters in the first of two media appearances that he hoped the North Koreans “fully understand the gravity of what I said.” He singled out Kim Jong-un, the North Korean leader, saying that Mr. Kim has gotten away with destabilizing the region for too long.
“This man will not get away with what he’s doing,” the president told reporters before the late afternoon meeting with Mr. Tillerson, Nikki R. Haley, the ambassador to the United Nations, and Lt. Gen. H. R. McMaster, the national security adviser. “If he utters one threat in the form of an overt threat” or takes action against the United States territory of Guam or against America’s allies, “he will truly regret it and he will regret it fast.”
As a practical matter, Mr. Trump’s comments do not necessarily indicate a change in military readiness. The motto of American forces based alongside allied troops in South Korea has long been “Ready to Fight Tonight,” mainly a slogan emphasizing preparedness rather than a statement of hostility.
United States Navy officials said Friday that despite Mr. Trump’s heightened rhetoric, the Navy has not repositioned any ships near the Korean Peninsula, nor were there any plans to, which would be a prelude to an American strike.
The business-as-usual posture from the Pentagon does not necessarily mean that the American military is not ready to strike North Korea, or defend American allies in the event of a Pyongyang strike. The nearly 25,000 American troops serving in South Korea pride themselves on being in a constant state of alert.
But military officials say that given how quickly North Korea could retaliate against an American strike — and that retaliation could encompass an attack on Seoul, home to more than 130,000 Americans — it is doubtful that the Defense Department would advise a strike without first moving assets and organizing an evacuation.
“It’s a couple of dogs barking at each other with a chain-link fence in the middle,” said Adm. Dennis C. Blair, the retired head of the Pacific Command and a former director of national intelligence. Any operation would involve extensive preparations and consultations, he noted. “You’d know that something big is afoot, and that is simply not the case now. In answer to the question, are we about to go to war? I’d say no.”
The Trump administration has repeatedly said its diplomatic initiative to pressure North Korea into abandoning its nuclear weapons and ballistic missile program is still in its early phases, with much work remaining to be done. Mr. Tillerson also has said that the United States was open to talks if North Korea stopped the series of missile tests that have rattled the region in recent weeks.
If Mr. Trump was hoping his sharp warnings would provoke a response from China, he chose an odd moment. Chinese leaders, including Mr. Xi, are largely focused on domestic politics. Top officials have gathered at Beidaihe, a seaside retreat more than 170 miles east of Beijing, to map out a once-every-five-years leadership reshuffle of the ruling Communist Party to take place this fall.
Bonnie S. Glaser, a senior adviser for Asia at the Center for Strategic and International Studies in Washington, said Chinese leaders would probably conclude that both Washington and Pyongyang are dangerous and unpredictable. “It’s unlikely that Xi will seek support from his colleagues for greater cooperation with an unpredictable U.S. president,” she said.
Analysts said that Beijing’s role in resolving the current crisis might be limited. “It’s unclear Beijing would have much of a role right now beyond their usual platitudes calling on all parties to exercise restraint,” said Ely Ratner, a senior fellow at the Council on Foreign Relations. “Neither Washington or Pyongyang is interested in the diplomatic solution Beijing has put on the table.”