Although he expressed optimism about the February 27-28 Hanoi summit in verbal testimony to the Senate Armed Services Committee, Admiral Philip Davidson, head of the Indo-Pacific Command, expressed doubts about North Korean intentions in his written submission to the panel.
Last week, Trump said he would hold his second meeting with Kim in the Vietnamese capital Hanoi on Feburary 27 and 28.
"North Korea has made clear its stance [on denuclearization] repeatedly and sufficiently before, including in leader Kim's New Year's Day speech".
After last year's summit, Trump announced a halt to joint military exercises with South Korea, saying they were expensive and paid for mostly by the US. Their first summit in Singapore last June resulted in Kim's vague commitment to "complete denuclearization of the Korean Peninsula", a term that his propaganda machine previously used when it argued it would only denuclearize after the USA withdraws its troops from South Korea.
Abrams also said the last time that North Korea launched a ballistic missile or conducted a nuclear weapons test was before the first Trump-Kim summit.
However, he said that action was reversible and added: "Much needs to be done to make meaningful progress".More news: Revitalised Man Utd a different prospect for injury-hit PSG, admits Tuchel
The Prime Minister said this when responding to a question whether Malaysia viewed the second summit between United States and North Korean leaders as a positive development to reopen its embassy in North Korea.
Kim pledged in Singapore to work toward denuclearization of the Korean peninsula and in September expressed willingness to permanently dismantle facilities at his country's main nuclear site of Yongbyon - in return for corresponding United States moves. South Korean officials pushed for a three-year deal keeping their annual contribution around $864 million.
The new deal must still be approved by South Korea's parliament, but it would boost its contribution to 1.03 trillion won (687.68 million pounds) from 960 billion won in 2018.
The State Department declined to comment.
The study by Stanford University's Center for International Security and Cooperation estimated the size of Pyongyang's arsenal at 30 nuclear weapons, bringing the possible current total up to 37.
However, it said North Korea's freeze in nuclear and missile testing since 2017 mean its weapons program probably poses less of a threat than it did at the end of that year. North Korea agreed to return to the United States some 50 boxes of remains believed to contain the bodies of missing American servicemembers from the Korean War.