North Korea is expected to hold a plenary meeting of the ruling Workers' Party of Korea this week to review policy performances in the first half, amid attention over whether it would discuss follow-up measures to implement a new partnership treaty signed with Russia.

In May, the WPK's politburo decided to hold a plenary meeting of the party's Central Committee in late June to review progress in its economic and other projects in the first half, without disclosing other details, such as the date of the meeting.

North Korea usually holds a party plenary meeting for a few days in June. But the upcoming gathering draws more attention due to the possibility that it could discuss detailed measures to expand cooperation with Russia following its signing with Moscow of the treaty of comprehensive strategic partnership.

North Korean leader Kim Jong-un and Russian President Vladimir Putin held a summit in Pyongyang on Wednesday and clinched the sweeping treaty that calls for providing military assistance without delay if either comes under attack.

Article 4 of the 23-point treaty could be seen as warranting automatic military intervention in the event of aggression on either country. That would amount to the restoration of a Cold War-era alliance for the first time in 28 years since a mutual defense treaty was scrapped in 1996.

The treaty also indicates North Korea and Russia could join hands in resisting international sanctions against Pyongyang's nuclear and missile programs. Article 16 of the treaty calls for both sides to oppose "unilateral coercive measures of an extraterritorial nature."

The new pact specifies science and technology, space, the peaceful use of nuclear power and artificial intelligence as among the areas for cooperation. This raises concerns that North Korea and Russia's cooperation in such fields could assist the North's development of weapons of mass destruction banned under UN sanctions.

Whether North Korea would ratify the treaty at the WPK meeting will also garner attention. Under the North's constitution, an "important treaty" can be ratified or scrapped solely by its leader Kim, though the Supreme People's Assembly (SPA), the North's parliament, approves ordinary treaties.

After this week's party plenary meeting, North Korea is widely expected to hold a key session of the SPA in a bid to revise the constitution. The North's leader earlier called for revising the constitution to define South Korea as the North's "primary foe" and clarify its territorial boundaries, including the maritime border.

Experts said at this week's WPK meeting, Kim may issue a message critical of the United States and South Korea over the allies' joint military drills scheduled for August.

Seoul and Washington plan to stage the annual Ulchi Freedom Shield in August, which the North has long denounced as a rehearsal for northern invasion.

Separately, the USS Theodore Roosevelt, a US nuclear-powered aircraft carrier, arrived in the southeastern port city of Busan on Saturday in a show of force against North Korea's military threats. The US, South Korea and Japan will hold their first-ever trilateral multidomain exercise later this month. (Yonhap)