The recent agreement between Russia and North Korea, reached by their leaders at a summit in Pyongyang, requires both countries to use all available means to provide immediate military assistance in the event of war, according to North Korean state media on Thursday.

Iran Press/Asia: Both North Korea’s Kim Jong Un and Russia’s Vladimir Putin had described the deal reached Wednesday as a major upgrade of bilateral relations, covering security, trade, investment, cultural and humanitarian ties. Outside observers said it could mark the strongest connection between Moscow and Pyongyang since the end of the Cold War.

The North’s official Korean Central News Agency on Thursday reported the language of the comprehensive strategic partnership agreement. The agency said Article 4 of the agreement states that if one of the countries gets invaded and is pushed into a state of war, the other must deploy “all means at its disposal without delay” to provide “military and other assistance.” But it also says that such actions must be in accordance with the laws of both countries and Article 51 of the United Nations Charter, which recognizes a U.N. member state’s right to self-defense.

The summit between Kim and Putin came as the U.S. and its allies expressed growing concern over a possible arms arrangement in which Pyongyang provides Moscow with munitions for the conflict in Ukraine, in exchange for economic assistance and technology transfers.

Following their summit, Kim said the two countries had a “fiery friendship,” and that the deal was their “strongest-ever treaty,” putting the relationship at the level of an alliance. He vowed full support for Russia in the conflict with Ukraine. Putin called it a “breakthrough document” reflecting shared desires to move relations to a higher level.

North Korea and the former Soviet Union signed a treaty in 1961, which experts say necessitated Moscow’s military intervention if the North came under attack. The deal was discarded after the collapse of the USSR, replaced by one in 2000 that offered weaker security assurances.

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