Ukrainian Defense Minister Oleksiy Reznikov has told CNN there will be a "really bloody massacre" if Russia decides to invade Ukraine, and warned that "Russian guys also will come back in the coffins," amid heightened alarm about troop movements on the nations' border.

Reznikov urged US President Joe Biden -- who was set to speak with Vladimir Putin of Russia in a video conference call on Tuesday -- to stand firm against Moscow.

"If I can advise President Biden, I would like him to articulate to Mr. Putin that no red lines from the Kremlin side should be here. The red line is here in Ukraine and the civilized world will react without hesitation," Reznikov told CNN in an exclusive interview Monday.

"The idea of not provoking Russia will not work," he added.

US and Western officials have expressed concern over the buildup of Russian forces on the Ukrainian border, with Secretary of State Antony Blinken saying last week that the US "must prepare for all contingencies."