It began with a peace move nobody wanted and ended with an experimental missile strike so rare in war Moscow gave a 30-minute heads-up to Washington.

The stakes have never been higher in the Ukraine-Russia war. In the week that saw the conflict pass its 1000th day, Western powers substantially boosted Ukraine's military arsenal - and the Kremlin made its loudest threats yet of a nuclear strike.

Russian president Vladimir Putin responded in a speech Thursday to Ukraine's attack with U.S. long-range missiles earlier this week. Moreover, the Kremlin leader stressed that Russia could not rule out attacking the countries from which Ukraine uses weapons.