North Korea traces of radioactive gases could be linked to the country’s February 12 test. A U.N. agency tasked with looking for signs of nuclear explosion shared the said findings from its monitoring stations.

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organizations (CTBTO), the U.N. agency in-charge of enforcing the ban of nuclear explosions by everyone, everywhere, stations in Japan and Russia have picked up “significant” traces of noble gases. Such gases accompany a nuclear explosion and say they “could be attributed” to the North’s test.

A statement from the Vienna-based organization said that its Japanese station is located around 600 miles from the test site where the traces could have come from. It says lower levels were picked up by the Russian site at Ussurisyk, but did not give its proximity to the test site.

It says that two types of xenon radioactive isotopes detected gave reliable information on the nuclear nature of the source.

NATO foreign ministers issued a statement Tuesday condemning “in the strongest possible terms” North Korea’s nuclear weapons program and threatening rhetoric. The statement said the communist country violated U.N. Security Council resolutions and jeopardized the prospects of lasting peace on the Korean peninsula.

Top White House aides told CBS News they doubt North Korea has the technological ability to miniaturize a nuclear bomb, put it on a long-range ballistic missile, and then fire and accurately target that missile.

Nonetheless, earlier this month, Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staffs, said there is enough uncertainty surrounding North Korea’s arsenal to justify increasing U.S. missile defense in the Pacific and also in Alaska.

Dempsey said that, “They [North Korea] have conducted several successful ballistic missile launches.” He added, “And in the absence of concrete evidence to the contrary we have to assume the worst case.”

North Korea has vowed to bolster its nuclear program in response to a U.S. State Department reporting which accused Pyongyang of human rights violations.

The Foreign Ministry in Pyongyang on Tuesday called the annual report of the State Department evidenced of a hostile policy by Washington targeted at toppling North Korea’s leadership.

The U.S. State Department last week cited defectors’ reports of extrajudicial killings, disappearances, arbitrary detention, arrests of political prisoners and torture in the document it publicly released.

Pyongyang also condemned a U.N. resolution approving a formal probe into suspected widespread rights violations in the country.