Deputy Prime Minister Taro Aso has singled out North Korea’s development of deliverable nuclear weapons as “the most significant geopolitical risk” to steady and broad-based economic growth.

“North Korea is the most significant geopolitical risk to the global economy at this juncture,” Aso said in a written statement Saturday to a meeting of the International Monetary Fund’s policy-setting panel in Washington, addressing what he views as “non-traditional risks” to global growth.

Aso didn’t attend the IMF session because he is currently in the middle of campaigning for the Oct. 22 Lower House election. Masatsugu Asakawa, vice finance minister for international affairs, attended the session in his place.

On the sidelines of the same meeting, U.S. Treasury Secretary Steven Mnuchin said he was working with America’s allies to develop new sanctions that could compel Pyongyang to curb its provocative behavior.

Mnuchin told reporters he had held discussions with other countries at the annual meetings of the IMF and World Bank in Washington on “further sanctions on North Korea.”

“We had very specific discussions with our counterparts” on ways to block Pyongyang from accessing funds for developing nuclear weapons and ballistic missiles, he said.

Mnuchin quoted U.S. President Donald Trump as saying Washington is “very determined to denuclearize the (Korean) Peninsula.”

The Treasury chief said North Korea and trade would be major issues during Trump’s visit to Japan and four other Asian countries next month.

“I think the purpose of the president’s trip is really to show U.S. leadership on these issues, and it will be a very, very important trip,” he said.

In a communique issued after the two-day meeting in Washington, the International Monetary and Financial Committee indirectly referred to North Korea as posing a risk to the upswing in global economic activity.

“Near-term risks are broadly balanced, but there is no room for complacency because medium-term economic risks are tilted to the downside and geopolitical tensions are rising,” the communique said.

Amid uncertainties over such risks, Aso, who doubles as finance minister, stressed the importance of ensuring financial market stability.

“We should reaffirm that excess volatility and disorderly movements in exchange rates can have adverse implications for economic and financial stability,” he said.

North Korea has continued to conduct missile and nuclear weapons tests in defiance of international condemnation and pressure as it pursues the ability to strike the mainland United States with a nuclear-tipped missile.

After testing two intercontinental ballistic missiles in July, Pyongyang on Sept. 3 conducted its sixth and most powerful nuclear test by detonating what it said was a hydrogen bomb capable of being mounted on an ICBM.

The U.S. and its allies and partners have been pressing North Korea to denuclearize. The Trump administration says it is keeping all options — including military action — on the table in dealing with the North.