Russian President Vladimir Putin deploys the nuclear-capable Iskander mobile short-range ballistic missile system to the Russian Kaliningrad exclave between Poland and Lithuania.
Poland and Lithuania join Ukraine in calling for stronger Western sanctions on Russia, with Polish President Andrzej Duda saying that "everything must be done" to prevent a potential Russian invasion of Ukraine, and that he was "absolutely against any policy of concessions to Russia".
Russian President Vladimir Putin says that the threat made by Belarus to cut their gas supply to Europe would be a breach of the contract with Russia and that such a threat may have been made in a fit of temper by Belarus's president Alexander Lukashenko.
Amidst ongoing protests against Alexander Lukashenko, Belarus abruptly closes its borders with Latvia, Lithuania, Poland, and Ukraine, while leaving its border with Russia open. Lukashenko insists that the move is to restrict the spread of COVID-19.
Russia's Ministry of Defence announces the first deployment of the Avangard hypersonic glide vehicle (HGV), calling it a "landmark event". According to President Vladimir Putin, the top speed is over Mach 20 and it puts Russia's military "ahead of all other nations".
3,000 U.S. troops are deployed in Poland as part of NATO's Operation Atlantic Resolve. Poland says that the deployment is a necessary response to Russian military exercises near its border and its intervention in Ukraine while Russia condemns the move as a "threat to national interests and security".
Russia deploys its S-400 missile system in Kaliningrad, an exclave between Poland and Lithuania, in response to "NATO expansion" near its borders. The United States criticizes the move as "destabilizing" to Europe. Russia announced the planned deployment over a decade ago.