WASHINGTON (Yonhap News) – The collapse of North Korea could occur abruptly and with little warning like that of East Germany, a U.S. think tank report said Friday.

"It is more a matter of 'when' that 'if' it will occur," said the 295-page report by Bruce Bennett, a senior defense analyst at RAND, a nonprofit research organization.

South Korea and the United States need to craft detailed contingency plans in case of the communist regime's collapse, which would be far more disastrous than the fall of East Germany, he pointed out.

The possible consequences include civil war in the North, a humanitarian crisis, the potential use and proliferation of the nation's chemical, biological and nuclear weapons, and even war with China, according to the report.

It stressed Seoul and Washington should immediately begin working with Beijing to prepare for a possible collapse of Pyongyang.   

"China recognizes that the United States will want to promptly reach the North Korean weapons of mass destruction sites north of Pyongyang to prevent their use or proliferation," it said.

"This U.S. interest could force China to seek to secure these facilities before the United States does."

China also may try to create a buffer zone inside North Korea to contain the refugees and prevent them from reaching China, where there are large pockets of ethnic Koreans, it added.

China, the North's key ally, has been reluctant to discuss the possibility of a North Korean collapse but some Chinese attitudes are changing, opening chances for consultations, it said.