Kim Jong-un, the leader of North Korea, has taken his boldest diplomatic gamble by supplying an estimated 11,000 troops and stockpiles of weapons to Russia to support its war against Ukraine.

The deployment provides timely foreign aid for Russia’s war efforts, with North Korean troops fighting alongside Russian forces in the Kursk region to help them retake territories lost to Ukraine. On Monday, Pentagon spokesman Maj. Gen. Pat Ryder said an unspecified number of North Korean soldiers had been killed and wounded there.

Sending the troops brings a range of benefits for North Korea, including much-needed cash and diplomatic leverage. Mr. Kim is receiving billions of dollars’ worth of food, oil, cash and advanced weapons systems from Russia that will help his regime endure international sanctions and upgrade its conventional armed forces, analysts say.

Mr. Kim had been in desperate need of such a breakthrough.

A triple whammy of incidents has rocked his dynastic regime over the past decade. First, American-led U.N. sanctions devastated North Korea’s economy by banning all its major exports, including coal, seafood, textiles and workers, as well as sharply curtailing its oil imports. Mr. Kim sought to lift the sanctions through direct diplomacy with former President Donald J. Trump. But the negotiations collapsed without an agreement in 2019,​ tarnishing Mr. Kim’s domestic image as an infallible leader. Then, the pandemic further crippled the North’s economy.

Pyongyang provides troops, missiles and howitzers.

North Korea looked more isolated than ever when it saw opportunities opening up as President Vladimir V. Putin’s invasion of Ukraine dragged on. Russia was using up troops and ammunition, and North Korea had plenty of both to offer. Its military is one of the world’s largest conventional armed forces, with 1.3 million members. And it kept huge stockpiles of artillery shells, rockets and other conventional weapons — many of them outdated — as well as new ballistic missiles it developed under Mr. Kim’s ambitious arms-buildup program.

The courtship started when North Korea invited Russia’s then-defense minister, Sergei Shoigu, to a massive weapons parade in Pyongyang in July last year. North Korean weapons began flowing into Russia soon afterward. When Mr. Putin invited Mr. Kim to a summit meeting in the Russian Far East in September last year, Russia showed off what it could offer North Korea in return, taking Mr. Kim on tours of a space launch facility, an aircraft factory and a naval ​port.