North Korea's latest appointment of its foreign minister as a member of the ruling party's politburo appears intended to brace the regime for possible high-level contact with the US and China, a Seoul think tank report said Tuesday.

North Korea on Saturday promoted Foreign Minister Ri Yong-ho to become a member of the political bureau of the Workers' Party of Korea (WPK) from an alternative member, a rare promotion of a top diplomat to a key party position.

Two North Korean foreign ministers doubled as members of the politburo during the period of late founder Kim Il-sung who ruled the country from 1945-1994, but there has been no such case since the era of late former leader Kim Jong-il who died in late 2011, according to a report by the state-run Institute for National Security Strategy.

"Ri's appointment appears aimed at preparing for potential high-level contact with the US and China," the report said. "In particular, it seems to reflect the need to match the title of Chinese diplomatic counterparts."

The move came amid an escalating war of words between North Korean leader Kim Jong-un and US President Donald Trump over Pyongyang's nuclear and missile programs.

Ri said in New York last month that his country could consider the detonation of a hydrogen bomb over the Pacific Ocean. The North's ruler vowed to take "high-level" retaliation against Washington after Trump threatened to "totally destroy" the North.

Cheong Seong-chang, a senior research fellow at the Sejong Institute, said that Ri's promotion appears to indicate an attempt by North Korea to break its deepening international isolation, which was sparked by the country's nuclear and missile programs.

The WPK held the plenary meeting to conduct the personnel reshuffle days before the 72nd anniversary of its founding, which falls on Tuesday.

Kim Yo-jong, the sister of the North's leader, was named an alternate member of the party's politburo, the top decision-making body. The move appears intended to further tighten the Kim family's control over the country.

The INSS said that Choe Ryong-hae, a close aide to leader Kim, may have taken the post of director of the WPK's organization and guidance department, which oversees the operation of party units and surveillance.

He was also named as a member of the party's central military commission in the latest reshuffle.

Meanwhile, Jong Kyong-thaek, who was newly picked as a member of the WPK's military commission, may have become the minister of state security, replacing spy chief Kim Won-hong, it said.

Kim is known to have been dismissed in mid-January following the ruling party's probe into the spy agency. He reappeared at a military parade in April, but it was not confirmed whether he was reinstated, as state media did not mention his title.

Pak Kwang-ho, an unknown North Korean official, may have replaced Kim Ki-nam, 91, director of the party's propaganda and agitation department, the report said.

In a surprise move, Pak was given the triple titles of member of the political bureau, vice chairman of the WPK's central committee and director of a department at Saturday's meeting. His background and career are not known, as his name has barely appeared in state media reports so far. (Yonhap)