U.S. spy agencies are reported to be seeing indications that North Korea is constructing new missiles.
According to the Washington Post, intelligence officials, speaking on the condition of anonymity, say North Korea is likely constructing at least one and possibly two missiles at a large research facility in Sanumdong.
The Post says new evidence, including satellite photographs, indicate the missiles are liquid-fueled intercontinental ballistic missiles and are being constructed at a factory that produced North Korea's first such missile capable of reaching the United States.
The paper says the new intelligence does not indicate that North Korea has expanded it capabilities, but rather that it is continuing to work on advanced weapons in the weeks following the Singapore summit between U.S. President Donald Trump and North Korean leader Kim Jong Un.
A senior State Department official had "no comment on matters of intelligence" when asked about the issue.
Intelligence officials told the Post while operations continue at the Sanumdong plant, work has come to a halt at the Sohae Satellite Launching Station on North Korea's northwest coast, where workers can be observed dismantling an engine test stand.
The paper, however, said many analysts and independent experts see the dismantling at Sohae as largely symbolic, and say the test stand could easily be rebuilt within months.
During last month's Singapore summit, Kim agreed "to complete denuclearization of the Korean Peninsula." But the document signed by Kim and Trump did not include details of how and when North Korea would denuclearize. Just after the summit, Trump tweeted that North Korea was no longer a nuclear threat.
Last week, U.S. Secretary of State Mike Pompeo said North Korea is still producing fuel for nuclear bombs despite pledges to give up its nuclear program.
He declined to answer questions about whether the North's nuclear program was still advancing and whether Pyongyang was looking to acquire ballistic missiles that could be launched from submarines.
But Pompeo told lawmakers that ongoing talks with North Korea were "verifiable evidence" of movement toward denuclearization. He said Kim understood the U.S. definition of denuclearization and that the North was not taking the Trump administration "for a ride."
Cindy Saine contributed to this story.