Not content with disturbing the peace in Europe, Russian President Vladimir Putin recently signed a comprehensive strategic partnership treaty with his North Korean counterpart, Kim Jong Un. As troubling to China’s leaders as it was to Western officials, the deal managed to shake up geopolitics in Northeast Asia and sent reverberations around the world.

Despite the strategic unease that Putin has provoked, the West must be careful neither to overestimate nor underestimate the treaty’s importance. The reasons for Putin’s recent trip to Pyongyang — his first visit in 24 years — were deeply pragmatic. Russia urgently needs North Korean ammunition, weapons and laborers to continue waging its war against Ukraine; and North Korea, as isolated as ever, longs for diplomatic support, as well as energy, food, cash and sensitive military technologies of the kind that only the Kremlin can provide.

For Kim, Russian military technologies are particularly important, because they could enable North Korean nuclear-armed intercontinental ballistic missiles to survive re-entry into Earth’s atmosphere and hit any target in the world without being intercepted by missile-defense systems. Moreover, if North Korea can produce quiet nuclear submarines with Russia’s help, they would pose a major security risk not just to South Korea and Japan, but also to the United States.