Satellite images in recent months have detected signs of preparations for a third atomic detonation at the North's test site. The regime's 2009 test followed a rocket firing by one month.
The U.N. Security Council is considering its response to the Wednesday flight of the North's Unha 3 rocket. While Pyongyang says the rocket carried a weather satellite into space, the United States and other nations lashed it as a violation of Security Council resolutions barring North Korean ballistic missile activities.
"North Korea will insist any sanctions are unjust, and if sanctions get toughened, the likelihood of North Korea carrying out a nuclear test is high," according to Baek Seung-joo of the Korea Institute of Defense Analyses.
The White House pledged that there would be "consequences" for the firing of the Unha 3, but did not offer specifics, Reuters reported.
"Members of the council must now work in a concerted fashion to send North Korea a clear message that its violations of U.N. Security Council resolutions have consequences," said U.S. Ambassador to the United Nations Susan Rice after the 15-nation body met on Wednesday. "In the days ahead, the United States will work with partners ... to pursue appropriate action."
The United States, European nations, Japan and South Korea support heightened international penalties against Pyongyang, according to a high-level Western envoy. Among the possible measures are more intensive monitoring of materials being shipped to or from North Korea, or preventing select North Korean officials from visiting other nations or accessing resources held in foreign states.
The key question is whether council veto holder China would accept any such moves against its longtime ally.