BEIJING (Kyodo) -- North Korea said Thursday its defense cooperation treaty with Russia took effect the previous day, state-run media reported, amid fears the pact will accelerate Pyongyang's military support for Moscow's invasion of Ukraine.

The Comprehensive Strategic Partnership treaty, which includes a provision for mutual assistance if either country comes under attack, was signed in June by North Korean leader Kim Jong Un and Russian President Vladimir Putin.

The pact effectively revives the countries' mutual defense obligation under a 1961 accord that became invalid following the Soviet Union's collapse in 1991.

The official Korean Central News Agency said the new treaty serves as a legal framework for "firmly defending the regional and global security environment in conformity with the common interests" of the two countries.

The "mighty" bilateral relations based on the pact will serve as "a strong driving force accelerating the establishment of independent and just multi-polarized world order without domination, subjugation and hegemony," KCNA said, in an apparent reference to the United States.

The treaty stipulates, "In case any one of the two sides is put in a state of war by an armed invasion from an individual state or several states, the other side shall provide military and other assistance with all means in its possession without delay," the news agency reported in June.

The pact, which will remain in "indefinite effect," also covers bilateral cooperation on trade, the economy, energy and technology, and other areas, KCNA said.

North Korea's Vice Foreign Minister Kim Jong Gyu and Russian counterpart Andrei Rudenko signed the protocol on exchange of ratification instruments in Moscow on Wednesday, the report said.

With the new pact's entry into force, the bilateral treaty of friendship, good neighborliness and cooperation concluded in 2000 became ineffective, according to KCNA.