The 1987 pact, which helps protect the security of the U.S. and its allies in Europe and the Far East, prohibits the United States and Russia from possessing, producing or test-flying a ground-launched cruise missile with a range of 300 to 3,400 miles.

Trump said Saturday that “Russia has violated the agreement. They have been violating it for many years.” The agreement has constrained the U.S. from developing new weapons, but Trump said America will begin developing them unless Russia and China agree not to possess or develop the weapons.