President Trump softened his tone on the prospect of using military force against North Korea in response to its efforts to build up its nuclear arsenal, vowing during a visit to South Korea to pursue peace through all other channels before considering a military strike.

"As we work together to solve this problem using all available tools short of military action, the United States stands prepared to defend itself and its allies using the full range of its unmatched military capabilities if need be," Trump said during a joint press conference with South Korean President Moon Jae-in on Tuesday.

Trump's more aggressive rhetoric about North Korea, which he has threatened to hit with "fire and fury" and which he has described as embarking on a "suicide mission," has worried South Koreans in the past. Most analysts believe any military conflict between the U.S. and North Korea would cost hundreds of thousands of South Korean lives.

Trump declined to say whether he thinks the economic pressure his administration has helped bring to bear on North Korea has made any difference on its conduct.

"I think you know me well enough to know that I don't like talking about whether I see success or not in a case such as this," Trump said. "We like to play our cards a little close to the vest."

But he did note some progress toward the goal of seeing the North Koreans give up their stock of nuclear weapons, which the administration has stated is its top priority in dealing with the Kim Jong Un regime.

"I think we're making great progress. I think we're showing great strength," Trump said. "I think they understand we have unparalleled strength."

The president noted the U.S. has positioned three aircraft carriers and a nuclear submarine in the Western Pacific. "We have many things happening that we hope, we hope — in fact, I'll go a step further, we hope to God we never have to use," Trump said.

His softer tone on North Korea, coming just weeks after he began calling its leader "Rocket Man" and threatened to "totally destroy" his regime, could signal an effort from the White House to reassure the South Koreans of the American commitment to its security.

H.R. McMaster, Trump's national security adviser, said last week that the president would use "whatever language he wants to" when discussing North Korea in Seoul after reporters asked whether Trump would change his tone to reflect the diplomatic challenges he might face in trying to assuage the concerns of nervous regional allies.

"I really think it makes sense for North Korea to come to the table and to make a deal that's good for the people of North Korea and the people of the world," Trump said. "I do see certain movement."