Experts warn that the expiration of a long-standing nuclear arms control treaty between the two superpowers could mark the start of a new nuclear rivalry.

A Russian official said Moscow is ready to respond with military measures if the United States deploys its missile defense program to Greenland.

Dmitry Medvedev, deputy chairman of Russia’s Security Council, criticised the United States over the operation that ousted Nicolas Maduro, saying it damaged the global system of international relation

Officials from Ukraine, the United States and European nations have quietly been discussing a new plan under which Western forces — including US troops — could be sent to Ukraine if Russia repeatedly violates a ceasefire agreement that might be negotiated to end the war.

For the first time since the war started, Ukraine has advanced into Russian territory. How did Russia allow Ukrainian tanks to roll right across the border? What is Putin's response to this attack on the homeland?