Poland and the United States sign a deal in Kraków allowing the United States to position an American anti-missile shield in Poland to defend Europe from the perceived threat of Iran and other countries: Russia objects.
The United States Secretary of State Mike Pompeo declares the 2015 nuclear accord with Iran as no longer in force. He also warns that the United States "is prepared to use our domestic authorities to impose consequences" for other countries that do not enforce the sanctions. Britain, France, Germany, China, and Russia oppose the snapback sanctions.
Poland's Minister of Defence Mariusz Błaszczak says he recently talked with U.S. officials in Washington D.C. about permanently stationing thousands of U.S. troops in Poland as a deterrent against Russia.
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.
Iran, the United States, the United Kingdom, France, Russia, People's Republic of China, Germany, and the European Union (the P5+1) reach a breakthrough agreement on the general framework for an agreement on Iran's nuclear program, but sign no verbal agreement or official document. The deadline for a full deal is June 30, 2015.