The brother of one of the Japanese nationals who was abducted by North Korea in the 1970s and 1980s and a former Japanese minister in charge of the abduction issue said Wednesday they have requested that the United States relist North Korea as a state sponsor of terrorism.

"I hope the U.S. government will put (North Korea) back on the state sponsor of terrorism list" as part of an effort to increase pressure on the leadership of Kim Jong Un, Takuya Yokota told reporters in Washington following a series of meetings with U.S. officials and lawmakers.

"A soft approach does not work when we negotiate with North Korea," said Yokota, secretary general of the Association of Families of Victims Kidnapped by North Korea, adding that "pressure is the only way to solve" the abduction issue.