WASHINGTON — President Donald Trump’s national security adviser said North Korea could be re-added to the list of state sponsors of terrorism as part of Trump’s strategy to counter the North’s growing nuclear threat.

“You’ll hear more about that soon, I think,” the adviser, H.R. McMaster, said as he briefed reporters on Trump’s five-nation tour of Asia, which starts Friday. North Korea’s nuclear threat will be a key focus of Trump’s meetings with the leaders of Japan, South Korea, China, Vietnam and the Philippines during the 12-day trip, Trump’s first official visit to the region.

McMaster cited the killing this year in a Malaysian airport of the estranged half brother of North Korea’s leader as an act of terrorism that could lead to the North’s placement on a list that currently includes only Iran, Sudan and Syria.

Malaysia has never directly accused North Korea, but South Korea’s spy agency has claimed the attack was part of a plot by North Korean leader Kim Jong Un to kill his brother, Kim Jong Nam.

“A regime who murders someone in a public airport using nerve agent, a despotic leader who murders his brother in that manner, that’s clearly an act of terrorism that fits in with a range of other actions,” McMaster said. Adding North Korea to the list of state sponsors of terrorism “is something that’s under consideration.”

Kim Jong Nam died in February after two women rubbed his face with a liquid later identified as VX nerve agent as he passed through the airport in Kuala Lumpur.

Under legislation enacted Aug. 2, the State Department is required to determine within 90 days, or around Thursday, whether North Korea meets the criteria of being a state sponsor of terrorism.

A State Department official said Thursday that officials are aware of the requirement and will provide the information to Congress when a determination has been made. The official was not authorized to speak publicly and spoke on condition of anonymity.

The U.S. kept North Korea on its terrorism blacklist for two decades after the 1987 bombing of a South Korean airliner killed 115 people. But President George W. Bush lifted the designation in 2008 to smooth the way for aid-for-disarmament negotiations.

Re-designating North Korea as a state sponsor of terrorism would be largely of symbolic significance. North Korea is heavily and increasingly sanctioned for its nuclear and missile activity in defiance of United Nations Security Council resolutions. Sanctions from a terror designation are unlikely to inflict significant, additional economic punishment.

Associated Press writer Matt Pennington contributed to this report.