South Korean intelligence sources have alleged that North Korea may soon conduct a new nuclear test.

“We have intelligence that North Korea may conduct its sixth nuclear test in the first week of April and are in the process of confirming this,” the Korea JoongAng daily quoted an unnamed South Korean military intelligence source as saying on Wednesday. “We have determined that North Korea is expected to finish all preparations for a nuclear test by March 31.”

Pyongyang has so far conducted five confirmed nuclear tests and numerous missile launches. The United Nations (UN) and the European Union (EU) have already imposed an array of crippling sanctions on North Korea over its missile and nuclear programs. Pyongyang says the programs are meant to guarantee security against potential US military aggression.

Last month, Pyongyang fired a missile into the sea off the east coast of the Korean Peninsula just as US President Donald Trump was hosting Japanese Prime Minister Shinzo Abe at Mar-a-Lago, Trump’s Florida retreat.

The North’s military also fired four ballistic missiles into the sea near Japanese territory earlier this month.