The United States urged North Korea on Tuesday to refrain from destabilizing rhetoric and actions after Pyongyang's top diplomat threatened the country could conduct yet another nuclear test depending on the "U.S.' attitude."

North Korean Foreign Minister Ri Yong-ho made the remark to reporters in Laos on the sidelines of a regional security forum, arguing that what he calls the U.S. "hostile policy" toward the North is increasingly becoming severe.

Ri also said the "biggest hostile act" by the U.S. is the recent imposition of sanctions on North Korean leader Kim Jong-un.

Earlier this month, the U.S. blacklisted Kim and other top North Korean officials for their roles in the country's human rights abuses.

"Whether we conduct an additional nuclear test or not depends entirely on the U.S.' attitude," Ri said.

In response, the U.S. State Department urged the North to refain from menacing rhetoric.

"We continue to call on North Korea to refrain from actions and rhetoric that further destabilize the region and focus instead taking concrete steps toward fulfilling its commitments and international obligations," said Katina Adams, a spokeswoman for the department's East Asia and Pacific Affairs Bureau, told Yonhap News Agency.

She also said the sanctions on the North's leader and other officials "are intended to promote accountability for North Korean officials responsible for serious human rights abuses and censorship."

"We will continue to work closely with the international community to sustain international attention on the deplorable human rights situation in North Korea, to press for the DPRK to stop these serious violations, to close its prison camps, to urge greater freedoms for North Koreans and to seek ways to advance accountability for those most responsible," she said.

North Korea carried out its fourth nuclear test in January and a long-range rocket launch the following month, drawing widespread international condemnation and leading the U.N. Security Council to impose the harshest sanctions ever imposed on the regime.

Earlier this month, the North Korea-monitoring website 38 North reported that satellite imagery shows high-level activity at the North's Punggye-ri nuclear test site, raising concern the regime may be preparing for another nuclear test.

South Korea's government also said the North is ready to conduct its fifth nuclear test at any time.

In Laos, U.S. Secretary of State John Kerry stressed the importance of pressuring the North, saying the country's actions "present a very serious threat not just to this region, but to international peace and security" and the regime has been flouting U.N. Security Council resolutions.

"It is critical for the world and for all countries to fully enforce the sanctions that have been imposed and we intend to do that," Kerry told reporters.

"North Korea, in January, did another nuclear test. In February, March, April, May, continually they have done missile tests. So together we are determined, all of us assembled here -- perhaps with one exception assembled here -- to make absolutely certain the DPRK understands that there are real consequences for these actions," he said. The exception is Ri. (Yonhap)