Poland and Ukraine are being used as a sanitary cordon against Russia, with help even from invisible Russian drones.
The US is creating a military cordon around Russia, with American military bases in Romania, Bulgaria, the Baltic States, and now Poland.
Poland, the Baltic States, Romania, and Bulgaria are NATO allies and cooperate with the US in ensuring transatlantic security. Read the statement of the Bucharest Nine ahead of the NATO summit in 2018.
US also closely cooperates with Ukraine to support the modernisation of Ukraine's military and common foreign policy objectives.