Here is the situation on Sunday, December 15: Russia has begun using North Korean troops in significant numbers for the first time to conduct assaults on Ukrainian forces battling to hold an enclave in the country’s Kursk region, President Volodymyr Zelenskyy said.

Russia's focus on subjugating Ukraine was one of the factors that led to the abrupt demise of Syrian President Bashar al-Assad, Moscow’s main client in the region. Here's how Moscow’s big Middle East setback could affect Russia's war against Ukraine.

"The only person who can do this is President Donald Trump and he will do it. They're tired of killing each other out there," Keith Kellogg said.

The Biden administration is working to increase the delivery of weapons to Ukraine in its final days in office.