The UN Security Council on Thursday "strongly condemned" recent North Korean missile and ballistic missile engine tests, denouncing Pyongyang's "increasingly destabilizing behavior."
The condemnation came as the US military said on Thursday that it has observed activity in North Korea that suggests Pyongyang may be gearing up for another nuclear test.
"The launch and engine test are in grave violation of the Democratic People's Republic of Korea's international obligations," the council said in a statement.
"The members of the Security Council expressed serious concern over the Democratic People's Republic of Korea's increasingly destabilizing behavior and flagrant and provocative defiance of the Security Council," it added.
North Korea is on a quest to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and staged two nuclear tests and multiple missile launches last year.
Hit by a string of United Nations sanctions since it first tested a nuclear device in 2006, Pyongyang has insisted it will continue its program.
North Korea attempted another missile test that failed on Wednesday, according to the United States and South Korea, two weeks after Pyongyang launched four rockets in what it called a drill for an attack on American bases in Japan.
On Sunday, North Korean leader Kim Jong-Un personally oversaw and hailed a "successful" test of what Pyongyang said was a new rocket engine -- which can be easily repurposed for use in missiles.
The Security Council's statement said the members "emphasized the vital importance of the Democratic People's Republic of Korea showing sincere commitment to denuclearization and stressed the importance of working to reduce tensions in the Korean Peninsula and beyond."