Thomas Maresca

Special to USA TODAY

SEOUL – A Pentagon report released Thursday described North Korea’s missile and nuclear program as an “extraordinary threat” to the United States, warning that the U.S. must “remain vigilant” despite ongoing diplomatic engagement with the North.

The Missile Defense Review report, introduced by President Donald Trump during a speech at the Pentagon, was released just hours ahead of a top North Korean envoy’s arrival in Washington to discuss a potential second summit between Trump and North Korean leader Kim Jong Un.

“While a possible new avenue to peace now exists with North Korea, it continues to pose an extraordinary threat and the United States must remain vigilant,” the report said.

Trump mentioned North Korea only in passing in his remarks, but the report emphasized that Pyongyang has invested considerable resources and undertaken extensive nuclear and missile testing “in order to realize the capability to threaten the U.S. homeland with missile attack.”

“As a result, North Korea has neared the time when it could credibly do so,” the report concluded.

Trump has underplayed the threat posed by North Korea in tweets and statements dating to his historic summit with Kim Jong Un last June. After his return from that meeting, which was held in Singapore, the president tweeted that “everybody can now feel much safer” and that "There is no longer a Nuclear Threat from North Korea."

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In recent weeks, Trump has continued to characterize Washington’s relationship with Pyongyang in glowing terms and has highlighted his administration’s diplomatic efforts.

"Now I say this, North Korea, we're doing very well," he said earlier this month. "And again, no rockets. There's no rockets. There's no anything. We're doing very well."

Vice President Mike Pence on Wednesday, however, noted that North Korea has still not taken “concrete steps” to dismantle its nuclear weapons program.

"While the president has started a promising dialogue with Chairman Kim, we still await concrete steps by North Korea to dismantle the nuclear weapons that threaten our people and our allies in the region," Pence said in a speech to U.S. ambassadors at the State Department.

With the arrival of North Korea’s top nuclear negotiator, Kim Yong Chol, in Washington on Thursday night, momentum appears to be building toward another summit. Neither the U.S. or North Korea have made any official announcements, but the envoy is expected to meet Friday with Secretary of State Mike Pompeo.

The communist nation of Vietnam is increasingly being touted as a likely site for the summit, with South Korean and Japanese media reporting that planning discussions have already taken place between U.S. and North Korean officials. Both the capital, Hanoi, and the coastal city of Danang have been cited as possible host locations.

Furthering the Vietnam speculation, Reuters reported Thursday that Kim Jong Un will be making an official state visit to Hanoi in February.

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Washington has in the past suggested that Vietnam, a communist nation with a rapidly developing economy, could serve as a model for North Korea.

A second Trump-Kim summit would look to further negotiations that have stalled out since their Singapore meeting, which produced a vaguely worded declaration that North Korea would work toward a “complete denuclearization of the Korean peninsula.”

Pyongyang is looking for relief of punishing international sanctions in exchange for steps it has already taken while Washington has been holding out for complete denuclearization first.

North Korea didn’t launch any missiles or test any nuclear weapons in 2018 and in May Pyongyang made a show of dismantling its Punggye-ri nuclear test site. But international inspectors have not been allowed to visit the site and research has shown that the isolated state continues to develop its ballistic weapons program at several locations.