US Defense Secretary Jim Mattis says any military attack on North Korea would be “tragic on an unbelievable scale” amid increasing tensions between Washington and Pyongyang.

U.S. Defense Secretary James Mattis gestures during a press briefing on the campaign to defeat ISIS at the Pentagon in Washington, U.S., May 19, 2017. REUTERS/Yuri Gripas

North Korea has recently conducted several missile tests and says it would not abandon its missile and nuclear programs unless the US ends its hostility toward the country.

In April, President Donald Trump warned that he would act “unilaterally” against Pyongyang, saying there was a chance for a “major conflict with North Korea.”

Mattis told a Pentagon news conference Friday that “we are going to continue to work the issue.”

“If this goes to a military solution, it’s going to be tragic on an unbelievable scale. So our effort is to work with the UN, work with China, work with Japan, work with South Korea to try to find a way out of this situation.”

On Sunday, North Korea test-launched an intermediate-range ballistic missile that many experts believe could be its most advanced so far. The missile flew some 700km (435 miles), reaching an altitude of 2,000km and landing in the sea west of Japan.

Mattis said the latest missile test showed North Korea was not heeding cautions from the international community.

“They (North Korea) clearly aren’t listening but there appears to be some impact by the Chinese working here. It’s not obviously perfect when they launch a missile.”

He also said that Pyongyang had probably learned a good deal from the test of what US officials believe was a KN-17 missile, which was thought to have survived re-entry to some degree.

“They went to a very high apogee and when it came down obviously from that altitude they probably learned a lot from it. But I’m not willing to characterize it beyond that right now,” Mattis said.

According to American experts, the latest missile, which reportedly can carry a nuclear warhead, could reach the US state of Hawaii if it was fired on a normal trajectory.

– Trump ordered to speed up fight against Daesh –

Elsewhere in his remarks, Mattis pointed to the US so-called campaign against Daesh in Syria and Iraq, saying Trump had ordered an “accelerated operation” against the terrorist group.

“He directed a tactical shift from shoving ISIS (Daesh) out of safe locations in an attrition fight to surrounding the enemy in their strongholds so we can annihilate ISIS.”

He went on to say that the US is leading a campaign that aims to “crush ISIS’s claim of invincibility” and “eradicate their ability to recruit and finance terrorist operations.”

His remarks come as the US military Thursday launched an attack against a convoy of the Syrian military heading towards the border near Jordan where Daesh terrorists are based.

Russia and Syria have condemned the airstrikes, saying the “brazen” attacks violate the Arab country’s sovereignty and show Washington’s claims of fighting terrorism are false.

Russian Deputy Foreign Minister Gennady Gatilov on Friday described as “unacceptable” the attacks, which also claimed the lives of civilians.

The US campaign against purported terrorist targets inside Syria and Iraq, which began in 2014, has led to the death of many civilians without any meaningful achievement.