U.S. to 'sharpen' economic pressure on North Korea in aftermath of latest nuclear test

The U.S. will do all it can with financial tools to oppose North Korea's nuclear weapons policy, because co-ordinated economic sanctions have been shown to work, U.S. Treasury Secretary Jack Lew says.

Treasury secretary says Washington will 'do everything we can' to curb Pyongyang's nuclear program

North Korean military personnel attend a rally in Pyongyang in January. The reclusive country will face continued economic pressure because of its latest nuclear test, according to U.S. Treasury Secretary Jack Lew. (Jon Chol Jin/Associated Press)

The U.S. will do all it can with financial tools to oppose North Korea's nuclear weapons policy, because co-ordinated economic sanctions have been shown to work, U.S. Treasury Secretary Jack Lew said on Monday.

"I think sanctions have effectively cut North Korea off from the global economy," Lew said three days after Pyongyang set off its most powerful nuclear blast to date and claimed to have mastered the ability to mount a warhead on a ballistic missile.

"North Korea is an enormous challenge, and we will do everything we can to keep the pressure on them," he said. "We will continue to sharpen financial tools as we can. The goal is to change the [North Korean nuclear weapons] policy."

He  added China's participation is very important.

"We've seen no sign of a change in policy," he said, but the United States is not about to relax sanctions. 

South Korea's Defence Ministry warned its neighbour could set off another nuclear test at any time. 

"The North is always ready for an additional nuclear test in the Punggye-ri area," the site of the North's five nuclear explosions so far, South Korean Defence Ministry spokesman Moon Sang-gyun told reporters on Monday. 

"North Korea has a tunnel where it can conduct an additional nuclear test," Moon said.

The South is pushing for more sanctions against Pyongyang to close what it says were loopholes left in the last United Nations Security Council resolution adopted in March.

Both China and Russia backed sanctions imposed in March following the North's January nuclear test, but their apparent ambivalence about fresh sanctions cast doubt on the Security Council's ability to form a consensus quickly.

"We expect that China, as one of the Security Council member states, should take this issue seriously and play a very constructive role to come up with a very effective and strong sanctions resolution," a South Korean foreign ministry official said.

The Security Council denounced the latest test on Friday and said it would begin work immediately on a resolution. The United States, Britain and France — three of the five veto-wielding permanent members — pushed for the 15-member body to impose new sanctions.