Kim Jong-nam was killed on Feb. 13 at an airport in Kuala Lumpur after being attacked by two Asian women with what appears to be a poisonous substance. According to Malaysian police, a total of eight North Koreans are suspected of involvement in the killing.

The killing, coupled with the North's test-firing of an intermediate-range ballistic missile earlier this month, has given rise to strong calls in Congress for putting the communist regime back on to the list of states sponsoring terrorism.

"The murder of Kim Jong-un's half-brother is yet another reminder of North Korea's brutality. I am in support of relisting North Korea as a State Sponsor of Terrorism," Gardner said in response to a question from Yonhap. "That's why I formally asked the Treasury Department to work with the State Department to investigate whether North Korea meets the criteria for re-designation."

Last week, Gardner and five other senators sent a joint letter to Treasury Secretary Steven Mnuchin, calling for greater pressure on the North, including expanding and tightening sanctions on the North and investigating whether the North merits designation as a state sponsor of terrorism.

"It's important that we prioritize the North Korean threat and pursue all available options, including secondary sanctions against entities that do business with Pyongyang, to put pressure on the regime and address its aggressive behavior," Gardner said.

North Korea was put on the US terrorism sponsor list for its 1987 midair bombing of a Korean Airlines flight that killed all 115 people aboard. But the U.S. administration of former President George W. Bush removed Pyongyang from the list in 2008 in exchange for progress in denuclearization talks.

Last month, Rep. Ted Poe (R-TX) introduced a bill in the House of Representatives calling for adding the North to the terrorism list. The legislation was referred last week to the Subcommittee on Asia and the Pacific, and the Subcommittee on Terrorism, Nonproliferation, and Trade.

After the North's missile test, Poe also issued a statement calling for the North's designation.

"Once upon a time, the United States had North Korea on the State Sponsors of Terrorism list. It is time to put little Kim back on that list because he is a world terrorist and a threat to world peace, and he has earned that distinction," he said.

Calls had spiked for putting the North back on the list after Pyongyang was found to be responsible for the 2014 cyberattack on Sony Pictures. But the State Department did not do so, saying relisting would only be symbolic without significant practical consequences.

The department left off the North from its latest terror sponsor list released last year, saying the regime in Pyongyang "is not known to have sponsored any terrorist acts since the bombing of a Korean Airlines flight in 1987."

The State Department has shown no reaction to last week's assassination of Kim Jong-nam, referring queries to Malaysian authorities. It also declined comment on the calls for the North's re-designation as a terror sponsor. (Yonhap)