NORTH KOREA FIRES UP H-BOMB : North Korea Says It Successfully Tested Hydrogen Nuclear Bomb (Update) The announcement followed detection of a 5.1 magnitude earthquake near North Korea's known nuclear test site.

 01/05/2016 09:53 pm ET

SEOUL, Jan 6 (Reuters) - North Korea said it had successfully conducted a test of a miniaturized hydrogen nuclear device on Wednesday morning.

The announcement on North Korean state TV followed detection of a 5.1 magnitude earthquake near its known nuclear test site earlier. The state claims the test was done in "self defense against the U.S. having numerous and humongous nuclear weapons."

The nuclear test, if confirmed, would be the fourth by the isolated country, which is under U.S. and UN sanctions for its nuclear and missile programs. 

The man-made earthquake was detected just after 10 a.m. Seoul time.

The White House, while it could not yet verify the success of the nuclear test, quickly condemned Pyongyang's violation of international law and promised to defend its South Korean ally. 

"We have consistently made clear that we will not accept it as a nuclear state," a White House spokesperson said in a statement. more