As Donald Trump seeks progress with North Korea at a second summit, the United States has a series of cards it can play including easing sanctions, signing a peace declaration or even pulling troops from South Korea.
After the historic handshake between the US president and North Korean leader Kim Jong Un in Singapore in June, Washington policymakers are adamant on the need for tangible concessions by Pyongyang on its nuclear program at the sequel meeting, which Trump says will take place around late February, with Vietnam the most likely venue.
But much depends on the mercurial Trump, who has declared his outreach to the longtime US adversary to be a diplomatic coup and angrily denounced criticism that his first summit was mere symbolism.
North Korea watchers believe that Kim's primary goal is relief from international sanctions and doubt he will suddenly give up his nuclear arsenal, which his dynastic regime has built for decades even through famine.
Complicated options on sanctions
When Kim met Trump, the first-ever summit between the two nations, North Korea was seen as seeking a treaty or at least statement formally ending the 1950-53 Korean War, which ended in an armistice.
But Victor Cha, the director of Asian studies at Georgetown University and former US negotiator with North Korea, said a peace declaration was ultimately symbolic.
"I don't think they would say no to it. A peace declaration would be a sign of non-hostile intent. But they want tangible evidence of non-hostile intent, which would be removing some of the sanctions," Cha said.
Secretary of State Mike Pompeo has vowed no let-up in sanctions until North Korea denuclearizes. And many US sanctions involve human rights or corruption laws and cannot be lifted without intervention by Congress, which is unlikely to be sympathetic.
But Cha said the United States could offer relief indirectly through South Korea's dovish government, working at the United Nations to remove sanctions that impede the restart of inter-Korean projects such as the Kaesong industrial complex.
The US is already preparing to ease restrictions on humanitarian aid and could offer to exchange liaison offices with Pyongyang, a step before diplomatic relations.
Focus on long-range missiles?
South Korea and Japan have increasingly wondered if Trump - who has made "America First" his guiding worldview - would focus on ridding North Korea of its fast-moving program of intercontinental ballistic missiles, which threaten the mainland United States.
Pompeo in recent interviews has described North Korea diplomacy as a way to protect Americans.
"Fairly or unfairly, that's being interpreted by our allies as a potential US willingness to cut a deal that only protects America and disregards the safety of our allies," said Bruce Klingner, a senior research fellow at the Heritage Foundation, a conservative Washington think tank.
The summit also comes amid a prolonged impasse in negotiations on how much South Korea should pay the United States to maintain its 28,500 troops in the country.
"There are concerns that Trump may be so eager for a success that he may agree to signing a peace declaration, signing an ICBM-only agreement and even reducing US forces on the peninsula either in return for perhaps a freeze on Yongbyon production or in response to the ongoing stalemate in Seoul," Klingner said.
Trump is a longstanding skeptic on the cost value of alliances and is demanding more from South Korea.
But any promise by Trump to Kim to pull out troops would likely meet wide opposition in Congress, fury from Japan's conservative government and quiet unease from South Korea, where President Moon Jae-in is more supportive of the US presence than previous left-wing leaders.
