South Korea’s president said Tuesday that North Korea has almost completed preparations to conduct a fifth nuclear test as the country has reportedly placed a new midrange missile on standby for an impending launch.

Pyongyang said two days ago it had successfully test-fired a ballistic missile from a submarine in a continuation of its weapons tests during ongoing South Korea-U.S. military drills. Seoul officials said they could not confirm whether Saturday’s test-firing was a success.

Meeting with senior South Korean journalists, President Park Geun-hye said that South Korea believes North Korea can conduct a nuclear test anytime it decides to do so. She didn’t elaborate on why South Korea made such an assessment.

Other South Korean officials have made similar recent comments without elaborating amid media reports of increased activity at the country’s main nuclear test site. Park said last week there were signs North Korea was preparing for a new nuclear test.

Speculation about a fifth nuclear test increased last month when the North’s state media cited leader Kim Jong Un as ordering a test of a nuclear warhead and ballistic missiles capable of carrying warheads.

North Korea conducted a fourth nuclear test in January and a long-range rocket launch in February and the country was subsequently slapped with tough U.N. sanctions. Park said Tuesday a further provocation by North Korea would only speed up its collapse, according to her office.

Analysts say a fifth test could happen before North Korea holds a ruling Workers’ Party congress in early May so that leader Kim Jong Un can burnish his image at home and further cement his grip on power.

Earlier Tuesday, South Korea’s Yonhap news agency cited an unidentified Seoul official as saying that the South’s military had unspecified evidence indicating North Korea would likely soon launch a midrange Musudan missile.

Seoul’s Defense Ministry said it had no such intelligence. South Korean officials often refuse to discuss North Korea’s weapons systems publicly because they involve confidential military intelligence.

Yonhap said the missile on standby is one of two Musudan missiles North Korea had earlier deployed in the northeast before it fired one earlier this month. U.S. officials said the earlier launch ended in failure.

A Musudan has a reach of 3,500 kilometers (2,180 miles), putting far-off U.S. military installments in Asia in range.

North Korea typically conducts more weapons tests when South Korean and U.S. troops conduct annual springtime drills that Pyongyang views as an invasion rehearsal. This year’s drills end later this week.

(AP)