Some lawmakers and experts are raising concerns about the president's unilateral authority to launch nuclear weapons as tensions with North Korea continue to escalate.
That designation was removed in 2008, when the North Korean government pledged to dismantle its nuclear program. The president says additional sanctions will be imposed.
The Trump administration is increasingly using economic sanctions to try to influence behavior in North Korea, Venezuela and Russia. But the strategy doesn't always work — and can backfire.
Despite the president's harsh words on China in the past, the leaders appear friendly and say they will cooperate on North Korea and work toward a balanced trade relationship.
The president says the U.S. is prepared to use "all available tools short of military action" to bring North Korea to the table, but that it would use the "full range" of military options if needed.
In Tokyo, Trump met relatives of Japanese citizens taken by North Korea in the 1970s. A handful have been freed over the years, but families are divided over the best way to gain release of the rest.
Putting regional pressure on the Kim Jong Un regime is expected to be the main push of the five-country tour that includes Japan, South Korea, China, Vietnam and the Philippines.