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.

In a stark warning to the West, President Putin said the attack with the intermediate-range Oreshnik missile was in retaliation for Kyiv’s use of U.S. and British longer-range missiles.

Russia has responded to Kyiv's use of long-range U.S-. and UK-made weapons by launching a powerful intercontinental ballistic missile (ICBM) for the first time in the 33-month-old war, according to Kyiv's air force. The U.S. has reopened its Kyiv embassy after airstrike worries saw it temporarily closed on Wednesday.