The top civilian at the Defense Department on Friday warned any military action in North Korea would result in devastation.
"As you know, if this goes to a military solution, it is going to be tragic on an unbelievable scale," Defense Secretary James Mattis said during a press conference Friday. "So our effort is to work with the U.N., work with China, work with Japan, work with South Korea to try to find a way out of this situation."
Mattis and Chairman of the Joint Chiefs Marine Gen. Joseph Dunford briefed reporters at the Pentagon on the Trump administration's plan to hasten the defeat of the Islamic State of Iraq and Syria, or ISIS.
Mattis was asked about how the U.S. is working to deal with provocations from North Korea, which under the leadership of Kim Jong Un has conducted an increasingly number of ballistic missile and nuclear tests.
"There's many different efforts underway," he said. "We have a whole of government approach to this as well, this issue as well. I spend as much time with the secretary of treasury as I do with the secretary of state as we try to craft a sustainable policy forward."
Earlier this week, Gen. Robin Rand, commander of Air Force Global Strike Command, said there are no plans at this time to add more strategic Air Force bombers to the Pacific region. The aircraft are often flown to act as a deterrent against the hostile nation.
The Air Force on April 26 conducted a test launch of an unarmed intercontinental ballistic missile that traveled 4,000 miles from Vandenberg Air Force Base, California, and landed in the South Pacific. The same test was conducted a week later.
When asked whether the recent tests were meant to send a message to Pyongyang, Dunford said what the U.S. has done so far has been routine.
"We did test ICBMs; It had nothing to do with North Korea," he told reporters. "It wasn't pointed in that direction. In order for us to make sure we have a safe, reliable and effective deterrent, we routinely test our ICBM in accordance with international protocols and in accordance with inspection regimes that are part of those international protocols."
The general added that for North Korea "to compare what they have been doing to threaten and intimidate their neighbors as well as the United States to our routine military exercises advertised well in advance with full transparency would be an unfair comparison."
Mattis said the U.S. and its allies will continue to apply pressure to North Korea, Mattis said.
"We're going to continue to breed the same kind of pressure internationally that we've been trying to. We're going to continue to work the issue," he said.
Airstrike in Syria
The U.S. defense officials also discussed Thursday's airstrike on the Syrian-Jordanian border that killed forces affiliated with Syrian President Bashar al-Assad.
Dunford called the airstrike a "self-defense" of U.S. forces also operating in the region.
Mattis said the pro-Syrian forces were backed by Iran.
"It was necessitated ... by offensive movement with offensive capability of what we believe were Iranian-directed -- I don't know there were Iranians on the ground, but by Iranian-directed forces inside an established and agreed-upon deconfliction zone," Mattis said.
The deconfliction zone is an area in which U.S. and Russian forces agreed not to operate. The zone previously applied to airspace but now includes ground territory, a defense official told Military.com. When exactly this definition was reclassified was not immediately clear.
"We believe they moved into that zone against the advice of the Russians," Mattis said. "Or -- or -- you know, apparently against the advice of the Russians. I can't confirm that either, but it looks like the Russians tried to dissuade them."
Russia reportedly made attempts to reach the pro-Assad forces on the ground, but were unsuccessful, the defense official said.