The U.S. and the U.K sent a stern warning to Russia and President Vladimir Putin on Tuesday over any new military aggression that Moscow directs against Ukraine. This comes as NATO’s 30 members met to discuss Moscow’s intentions for massing 90,000 troops on the border with Ukraine, a former Soviet republic.

Meanwhile, Putin issued a warning of his own. He said that NATO and the U.S. deploying troops to Ukraine is a red line for Russia and would trigger a strong response. Both sides claim that they are worried about troops being massed on the border. 

Amid this morass of rising tensions and tough talk comes news that Russia and Belarus are going to conduct more joint military drills to “cover our southern borders” according to Belarus government officials. 

Ukrainian officials are worried about the Russian troops on their border. The troops had taken part in military drills earlier this year and remained with much of their equipment.