Russian President Vladimir Putin said Sunday that the new inclusion of Western long-range missile systems in Ukraine's defenses would lead Moscow to hit “objects that we haven't yet struck.”

Smoke billowed from Kyiv, hit by airstrikes after a lull in assaults on the capital city. 

Putin's threat came only days after the U.S. announced it was giving Ukraine advanced weaponry. 

Military analysts say Russia is hoping to overrun the embattled eastern Donbas region, where Russia-backed separatists have fought the Ukrainian government for years, before any weapons that might turn the tide arrive. The Pentagon said earlier this week it will take at least three weeks to get the precision U.S. weapons and trained troops onto the battlefield.