North Korea has continued to draw international ire following a nuclear test Monday by reportedly testing several short-range missiles and threatening to set aside the Korean War armistice of 1953.

The underground test this week was the country's second, following its 2006 entry into the nuclear club, and was about five times more powerful than its predecessor, according to an analysis by seismologists at Columbia University’s Lamont-Doherty Earth Observatory. Lamont's Paul G. Richards and Won-Young Kim, who wrote a feature for Scientific American in March on nuclear monitoring, estimate that the blast was several kilotons in force. The action drew condemnation from across the globe, even from China, a traditional ally.

Support from China and Russia, which has been tough to come by in the past—including after North Korea's controversial rocket launch last month—will be critical to adopting stronger U.N. security council sanctions against North Korea. The New York Times reports that Russia was "surprisingly adamant" about the latest test and that "Vitaly I. Churkin, the Russian ambassador to the United Nations, said that the world had to face down threats to the Nuclear Nonproliferation Treaty, which many view on the brink of collapse, and the still-unapproved Comprehensive Test Ban Treaty." In a statement from the U.N., Churkin said that the council was working on a resolution to address North Korea's actions.

The Comprehensive Test Ban Treaty (CTBT), which President Obama has expressed support for, will not enter into force until the U.S. and eight other countries, including North Korea, agree to ratify it. (The other holdouts are India, Pakistan, Indonesia, Egypt, China, Israel and Iran.) Last month we reported on two proposed paths to reducing the threat of nuclear weapons, including one that sidesteps the CTBT in favor of a radical rethinking of U.S. nuclear policy.

Yesterday South Korea announced its endorsement of the Proliferation Security Initiative (PSI), a U.S.-led international effort to curb trafficking of weapons of mass destruction and their components. In response, North Korea stepped up its rhetoric, declaring in a statement that it "will regard any hostile actions against [North Korea], including checkup and inspection of its peaceful vessels, as an unpardonable encroachment on ... sovereignty and counter them with prompt and strong military strikes," according to South Korea's Yonhap news agency. "Our revolutionary armed forces, as they have already declared, will regard the [South Korean president's] group of traitors' 'full participation' in the PSI as a declaration of war."

Map of seismic shocks from blast: USGS/National Earthquake Information Center