U.S. President Donald Trump and North Korean leader Kim Jong Un will likely focus on concrete, verifiable denuclearization steps by Pyongyang in return for concessions from Washington, at a two-day summit starting Wednesday in Hanoi.

Trump and Kim, who both arrived in the Vietnamese capital Tuesday, are expected to discuss the dismantlement of North Korea's main Yongbyon nuclear complex in exchange for a declaration of a formal end to the 1950-1953 Korean War, or partial sanctions relief.

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The United States aims to hammer out a joint statement showing tangible progress beyond the vague commitments agreed to by Trump and Kim at their previous meeting -- the first-ever U.S.-North Korea summit -- in Singapore last June.

There, Kim promised to work toward "complete" denuclearization of the Korean Peninsula, while Trump committed to providing security guarantees to Pyongyang.

As he did before, Trump -- at the request of Japanese Prime Minister Shinzo Abe -- is also expected to push Kim to resolve the issue of North Korea's abduction of Japanese nationals in the 1970s and 1980s.

On Monday, Trump expressed hope that Kim will make a "wise decision" to rid North Korea of nuclear weapons and ballistic missiles.

"With complete Denuclearization, North Korea will rapidly become an Economic Powerhouse," he tweeted, alluding to its potential for growth, and geographic location between China, Russia and South Korea.

"Without it, just more of the same," he added.

Similarly, the White House said last week that the United States and its partners are prepared to explore how to mobilize investment, improve infrastructure and enhance food security "should North Korea follow through on its commitment to complete denuclearization."

Yet since the Singapore summit, there have been few conciliatory signs, with the United States demanding North Korea dismantle its arsenal with international verification, and Pyongyang calling for a lifting of sanctions.

North Korea has also sought an end-of-war declaration to the 1950s conflict as a first step toward guaranteeing its security. Advocates say such a confidence-building measure would facilitate denuclearization.

Such a statement is not legally binding and would only represent a symbolic end to the war, which ended with an armistice rather than a peace treaty.

Aside from a possible deal involving Yongbyon, Kim may offer to extend North Korea's nuclear and missile testing hiatus, to promise to limit its existing arsenal, as well as to allow the United States and other parties to verify the shuttering of Pyongyang's main missile engine test site and the closure of the only known nuclear test site.

Yongbyon came to the fore when Kim told South Korean President Moon Jae In last September in Pyongyang that he is prepared to permanently dismantle the site, housing facilities to produce plutonium and highly enriched uranium -- materials used in bombs -- if the United States takes "corresponding measures."

"A real step, a demonstrable, verifiable step, is something that I know President Trump is very focused on achieving," U.S. Secretary of State Mike Pompeo told CNN on Sunday, without providing details.

While some argue a verifiable dismantlement of Yongbyon, about 90 kilometers north of Pyongyang, would significantly curb production of new nuclear weapons, others say that alone would not lead to a reduction of what experts estimate is a stockpile of between 30 and 60 nuclear warheads.

There are also known to be other clandestine fissile material production facilities and programs in the country.

Corresponding concessions from the United States may include continued suspension of joint military exercises with South Korea, allowing Seoul to seek exemption from U.N. sanctions on North Korea for inter-Korean economic cooperation projects, and the opening of a liaison office in Pyongyang.

Despite Trump's proclamation after the June summit that "there is no longer a nuclear threat from North Korea," it has apparently continued production of fissile material, and its missile programs, while suspending nuclear and missile testing for more than a year.

"I am very hopeful that we'll make a substantial step towards achieving the full denuclearization in a verifiable way in North Korea," said Pompeo, who will participate in the Hanoi summit.

"The South Koreans, the Japanese, have been great partners in this, and we're very hopeful we can get a good outcome in the days ahead."