North Korea may be ramping up efforts to develop its nuclear weapons program since President Donald Trump and North Korean leader Kim Jong-Un first met at a Singapore summit last year.

The Wall Street Journal first reported that intelligence analysts are concluding that the secretive state is accelerating its production of long-range missiles and fissile material, both key components in making nuclear weapons.

The revelation comes after North Korea unveiled a new submarine that could launch nuclear weapons and fired two short-range missiles off its coast, flouting a UN ban on such testing.

Up to now, Trump has defended his negotiations with the North Korean leader, saying they've been a success because the country has not engaged in serious missile testing.

Visit Business Insider's homepage for more stories.

North Korea may be ramping up efforts to develop its nuclear weapons program since President Donald Trump and North Korean leader Kim Jong-Un first met at a Singapore summit last year.

The Wall Street Journal first reported that intelligence analysts have concluded that the secretive state is accelerating its production of long-range missiles and fissile material, both key components in making nuclear weapons.

Analysts have pored over satellite imagery of the reclusive state to discover the movement of shipping containers and trucks at crucial weapons facilities in the northern part of the country, according to The Wall Street Journal. These same analysts are estimating Pyongyang now has between 20 and 60 nuclear weapons.

The reports come after North Korea recently fired two short-range missiles off its coast, flouting a UN ban on such testing. The hermit kingdom has also unveiled a new submarine with possible nuclear-launch capabilities.

Read more: Close analysis of Kim Jong Un's new nuclear-missile submarine reveals it's bound for a suicide mission

Up to now, Trump has defended his ongoing negotiations with the North Korean leader, saying they've been a success because the country has not engaged in serious missile testing. Kim "promised he wouldn't be testing" nuclear weapons, Trump said in an interview last month with ABC News.

Read more: North Korea's latest missile test was an attempt to get Trump's attention after failed nuclear talks, experts say

The discoveries have been publicly met with shrugs by Trump administration officials so far. In an interview with Fox News, Secretary of State Mike Pompeo was asked about North Korea's new submarine and whether its unveiling could set back future negotiations over its nuclear program.

Pompeo responded, "I went to a defense facility. We all go look at our militaries, and we all take pictures of them."

Correction: The Wall Street Journal corrected its original reporting stating analysts at the US Defense Intelligence Agency said that North Korea could have expanded its nuclear weapons arsenal by 12 bombs since the June 2018 Trump-Kim summit meeting in Singapore. This post has been updated to reflect that.