The United States pulled out of the 1987 Intermediate-Range Nuclear Forces Treaty that required the US and Russia to destroy ground-launched ballistic and cruise missiles with ranges of between 500 and 5500 kilometers.

United States

From CNN and the New York Times

President Trump argued that Russia has failed to adhere to the treaty, and that US compliance inhibits the ability to negotiate with China, which is not currently bound by any treaties on their nuclear missiles. In comments on Saturday, Trump appeared to express an interest in pursuing a trilateral agreement in which all three countries would be bound by a single standard.

Europe

From Deutsche Welle

Russia immediately condemned the move as did Germany, whose foreign minister said the decision “raises difficult questions for us and Europe.” Britain, on the other hand, firmly supported the US and expressed the belief that Russia was responsible for the failure of the treaty.

China

From the South China Morning Post

Though the Chinese Foreign Ministry has not yet commented on the decision, several scholars are pointing to China’s ongoing military expansion as the ultimate target.  China has two series of missiles with ranges of up to 15,000 kilometers – putting the entire US within striking distance.