(CNN)As Tuesday's landmark summit between the leaders of the United States and North Korea drew to a close, questions remained for US allies in East Asia as to what Donald Trump and Kim Jong Un's budding relationship will mean for the region.
A document signed by the two men committed the US and North Korea to join efforts to "build a lasting and stable peace regime on the Korean Peninsula" and "to work toward the complete denuclearization of the Korean Peninsula."
Trump sought to clarify the specifics of that agreement in a news conference after the summit, but in doing so, revealed details that appeared to upend decades of US policy in Asia.
Trump outlined a vision of an Asian geopolitical landscape that included a significantly reduced US military presence, promising to end joint US-South Korean military exercises and eventually withdraw US troops from the Korean Peninsula.
Any suggestion of a potential removal of US power will likely spark concerns both in Tokyo and Seoul, where US troops have been stationed since the 1950s.
"I want to get our soldiers out. I want to bring our soldiers back home," Trump said. "But that's not part of the equation right now. I hope it will be eventually."
Trump also said he planed to halt what he called "war games" on the Korean Peninsula, likely a reference to the joint military exercises between the US and South Korea, touting the cancellation as cost saving measure.
Moon's all in
Regional powers have publicly pledged their support for the talks, following last year's heightened tensions and threats of nuclear war.
Other than Trump and Kim, perhaps no other leader had as much riding on the outcome of the talks as South Korean President Moon Jae-in -- who said he "didn't sleep a wink" the night before Tuesday's summit.
"Seventy years of division and hostility, however, have cast a dark shadow that makes it difficult to believe what is actually taking place before our very eyes," Moon said following the summit.
"Leaving dark days of war and conflict behind, we will write a new chapter of peace and cooperation. We will be there together with North Korea along the way."
In a phone conversation with Trump Tuesday evening, Moon said that the summit had "laid a great foundation for peace, not only for the Korean peninsula but for the world," according to Kim Eui-kyeom, a spokesman for the presidential Blue House.
During the call, the two leaders agreed to work together more closely to ensure the contents of the agreement are fully implemented, he added.
It was the second phone call between the leaders in two days, which the spokesman described as unprecedented in US-South Korea diplomatic history.
Moon has played the role of interlocutor between Trump and Kim, helping to set up what he called the "meeting of the century."
He spearheaded diplomatic efforts with the North by using the PyeongChang Winter Olympics as an opportunity to mend fences with Pyongyang. Moon would go on to meet with Kim at the end of April for the first inter-Korean summit in more than a decade.
But even mentioning the removal of troops in South Korea could be a bridge too far for Seoul, especially among its conservative and pro-American voters.
A smaller US military footprint in Asia would leave both South Korea and neighboring Japan exposed if North Korea were to undertake aggressive behavior or military provocations.
"The crown jewel of the deterrent largely is the bilateral military exercises," said Jonathan Berkshire Miller, an analyst at the Japan Institute for International Affairs.
"That sort of language, that these crucial elements of alliance deterrence are actually a pain in the butt, that doesn't go over very well in Japan," said Berkshire Miller.
In addition to protecting South Korea and Japan from the threat of North Korean missile strike, the US' presence in the region has acted as a counterweight to China.
Seoul and Tokyo would have to take a second look at their defense capabilities, perhaps even bolster them, should Washington choose to pull back -- something US Defense Secretary James Mattis said earlier this month would not be part of Trump's initial negotiations with Kim Jong Un.
Colonel Chad Carroll, a spokesman for US Forces Korea (USFK), told CNN "we here at USFK received no official updated guidance on execution or cessation in any upcoming training exercises."
Seoul and Washington maintain the drills are defensive in nature and meant to maintain the readiness of their forces, but Pyongyang has always viewed them as hostile, and in some cases as preparation for an invasion.
A win for China?
China appears to be another big winner of Tuesday's talks. Its foreign minister, Wang Yi, said Tuesday the summit was of "great significance" and a positive step forward.
But it also got Washington and Pyongyang to abide by a deal it proposed last year, albeit without Trump and Kim acknowledging it.
Moscow and Beijing both championed a so-called "freeze for freeze" deal, in which Washington and Seoul would pause military exercises and Pyongyang would stop weapons testing.
Both North Korea and the United States rejected the proposal out of hand when it was first proposed. Now, it appears that China has gotten its wish, with both sides halting those activities.
And the eventual removal of troops is music to Chinese President Xi Jinping's ears.
China has long been opposed to the American military presence in Japan and South Korea, worried the troops and military equipment on Beijing's doorstep was less about countering North Korean and more about containing a rising and powerful China.
To date, Beijing has been an important partner in Trump's maximum pressure campaign to diplomatically isolate North Korea and punish it economically, as it make makes up for about 90% of all of Pyongyang's foreign trade.
Trump said Tuesday that sanctions will remain in place until "we are sure the nukes are no longer a factor," but it's unclear if China will continue to vigorously enforce them.
There have been reports of increased trade on the country's border with North Korea, and Foreign Minister Wang told reporters Tuesday that sanctions could be adjusted.
"China always holds the view that sanctions are not the goal. Actions by the UN Security Council should support and coordinate with the current diplomatic dialogues and efforts on the denuclearization of the Korean Peninsula, and the promotion of a political settlement on the peninsula issue," he said.
Abe's small victory
Trump also said he confronted Kim about North Korea's kidnapping of Japanese citizens in the 1970s and 1980s, something Japanese Prime Minister Shinzo Abe thanked the US President for later in the day.
The abduction issue is a highly emotional topic in Japan, and something Abe says must be addressed before Tokyo normalizes relations with Pyongyang.
Kim and Trump sign their declaration in Singapore on Tuesday.
The abduction issue is the issue that I would like to squarely face with NK for the solution."
"North Korea has plentiful resources and labor, if it walks in the right path, it can draw a bright future," Abe said earlier Tuesday.
