Ukrainian Defense Minister Oleksiy Reznikov told CNN in an interview on Monday that Ukraine will continue to hold its ground against Russia after the latter had amassed some 90,000 troops near the countries’ shared border.

Reznikov warned that there would be a “really bloody massacre” is Russia chooses to invade. “Russian guys also will come back in coffins,” he told the outlet.

The minister encouraged U.S. President Joe Biden – who is speaking with Russian President Vladimir Putin on Tuesday – to relay a message from Ukraine. “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,” he said.

The U.S. is currently estimating that Russia could build up a force of around 175,000 troops to invade Ukraine. The Ukrainian representative, however, believes this is an underestimate. 

“We have 250,000 official … members of our army. Plus, I said 400,000 veterans and 200,000 reservists. 175,000 (is) not enough to go to Ukraine,” Reznikov said, adding that a Russian invasion could also lead to the “disastrous” reality of between 4 to 5 million Ukrainians seeking refuge across Europe. 

Ukraine has requested military aid and equipment from its allies, but has insisted it will not request troops. “We don’t need troops, because I think it’s not so fair that American soldiers will die in Ukraine. No, we don’t need it,” said Reznikov. 

On Russia’s motives for the troop build-up and constant threat of attack, Reznikov told CNN that he believes Putin’s motives are to generate fear and disturbance across Ukraine and prevent it from joining NATO and gaining EU membership. 

“It’s a main goal of them (Russia) to make destabilization process inside of our country, to stop us in our way. But we go into the NATO ally, we’re going to EU,” he said.