Tit-for-tat moves this week included the use of American-made ballistic missiles to strike inside Russia, and new nuclear threats from Moscow. Neither appear to have influenced the war on the ground.

The United States believes that Russia fired a never-before-fielded intermediate-range ballistic missile on Thursday in its attack on Ukraine, an escalation that analysts say could have implications for European missile defense.

Russia provided North Korea with missiles in exchange for sending troops to Ukraine, according to a senior South Korean official.

The United States expects that thousands of North Korean troops massing in Russia will "soon" enter combat against Ukraine, Pentagon chief Lloyd Austin said Saturday. About 10,000 North Korean soldiers were believed to be based in the Russian border region of Kursk,

President Joe Biden has revised U.S. policy to permit Ukraine's use of American-supplied long-range missiles against Russian targets. This decision responds to North Korea deploying approximately 11,000 troops to Russia's Kursk region,

Kim Jong-un’s decision to send troops to fight on Russia’s side in the Ukraine War has naturally spurred much speculation about North Korea’s motives. Why did Kim Jong-un decide to plunge North Korea into its first major war in more than seventy years?

The U.S., South Korea and others say North Korea has sent more than 10,000 troops to Russia to support its war against Ukraine.

Russia reportedly provided North Korea with oil, anti-air missiles and economic help in exchange for troops to support Moscow's war on Ukraine.