A top US Navy commander on Wednesday pushed for a "sense of urgency" over North Korea's nuclear and missile development, stressing it even threatens Pyongyang's allies China and Russia.
Admiral Harry Harris, who heads the Pacific Command, spoke during a visit to Japan after North Korea's latest ballistic missile test raised further alarm over the pace of its weapons development.
North Korea on Sunday launched what appeared to be its longest-range ballistic missile yet, claiming it was capable of carrying a "heavy nuclear warhead" in a test aimed at bringing the US mainland within reach.
Pyongyang carried out two atomic tests last year, and has accelerated its missile launch programme, despite tough UN sanctions aimed at denying leader Kim Jong-Un the hard currency needed to fund his weapons ambitions.
"In every test he (Kim) makes, it's a success because it takes North Korea one step closer to be able to deliver a nuclear-tipped missile anywhere in the world," Harris said.
"I must assume Kim Jong-Un's claims are the truth, because I know his aspirations certainly are... That should provide all of us with a sense of urgency to address this problem now," he added.
The United States said the missile landed close to Russian territory, but Moscow later said it fell in the ocean about 500 kilometres (310 miles) away and posed no threat.
Harris, however, stressed that China and Russia, the North's traditional backers, can no longer look the other way.
"The dangerous behaviour by North Korea is not just a threat to the Korean peninsula... it's a threat to China, it's a threat to Russia," Harris told a an academic forum in Tokyo.
Russian President Vladimir Putin said the test was dangerous, but warned against attempts to "intimidate" Pyongyang.
Harris is visiting Tokyo to discuss North Korea and other issues with Japanese officials, including Prime Minister Shinzo Abe, who he met Tuesday.
He called for nations to "ratchet up sanctions" on the North, reiterating that the world needs to "bring Kim Jong-Un to his senses, not to his knees".
After the missile launch on Sunday, the United States, Japan and South Korea called a UN Security Council meeting to press North Korea to change course and dismantle its missile and nuclear programmes.
Earlier this month naval exercises were conducted in the Sea of Japan (East Sea) by the aircraft carrier USS Carl Vinson, with South Korean and Japanese aircraft also taking part.
The US vessel is reportedly still patrolling in the region.