North Korean leader Kim Jong Un hailed a December rocket launch in a speech to mark the New Year. In a transcript published by the state-run Korean Central News Agency, Kim described the launch as a "great event ... (that) clearly showed that Korea does what it is determined to do."
A failed rocket launch by North Korean in April brought concerns the reclusive regime was preparing to test a nuclear device. Similar launches in 2006 and 2009 coincided with North Korea's first nuclear tests.
Victoria Nuland, a spokeswoman for the U.S. State Department, said Pyongyang's policies weren't conducive to diplomatic engagement.
"We obviously take note of the speech but we have to judge the Democratic People's Republic of Korea not by its words but by its actions," she said.
South Korea's Yonhap news agency reported that diplomats from Seoul may push for formal action at the U.N. Security Council due to the rocket launch.
Nuland said Kim can either reach out to the international community "or he can continue on the course that he's on, which is only serving to further isolate his country and further impoverish his people."