The comments are likely to fuel growing scepticism over whether Pyongyang intends to give up the nuclear weapons program that it has long considered essential to its security.
The researchers’ findings were based on satellite imagery, defector interviews and interviews with intelligence and government officials.
Speaking to reporters before and after a closed-door UN Security Council meeting on North Korea sanctions, Haley said it is now North Korea’s turn to act.
Despite a flurry of diplomacy on and around the peninsula, differences are emerging between Seoul and Washington.
However, experts questioned what Pompeo had achieved on Sunday on his fourth visit to Pyongyang this year.
Pompeo met with the North Korean leader in Pyongyang on Sunday to rekindle stalled denuclearisation talks following a landmark summit between Kim and US President Donald Trump in Singapore.
Washington wants North Korea to first provide a complete inventory of its weapons programs and take irreversible steps to give up its arsenal.
South Korean officials hope the visit might revive momentum for talks on denuclearisation between the United States and North Korea.
Trump’s statement came a day after his defense secretary hinted that the drills, which North Korea denounces as rehearsals for invasion, could resume.
A spokesman for South Korea’s presidential Blue House said on Sunday officials hoped such details would be decided at Monday’s talks.
Vice President Mike Pence hailed the remains’ arrival in Hawaii as evidence of the success of President Donald Trump’s landmark summit in June with North Koran leader Kim Jong Un.
According to the US official who spoke to Reuters, one photo showed a truck and covered trailer similar to those the North has used to move its ICBMs.
Washington has reportedly devised a programme to dismantle North Korea’s weapons of mass destruction and ballistic missile programs in a year.
Pompeo was also questioned about Trump’s saying after the summit with Kim that North Korea no longer posed a nuclear threat, an assertion questioned by analysts and mocked by Democrats.
Trump and Kim promised in a joint statement to work toward the “denuclearisation” of the Korean Peninsula, and the United States promised its Cold War foe security guarantees.
With cameras of the world’s press trained on them, Trump and Kim displayed an initial atmosphere of bonhomie.
US officials believe there was some dissension in the military about Kim’s approaches to South Korea and the United States.
US-ally South Korea and North Korea have technically been at war for decades, even though the Korean War’s military combat ended in 1953 because a peace agreement was never signed.
