President Donald Trump says he will pull the United States from the intermediate range nuclear forces treaty with Russia.
Mr Trump says Moscow has violated the agreement, but provided no details.
The 1987 pact helps to protect the security of the United States and its allies in Europe and the Far East. It prohibits the US and Russia from possessing, producing or test-flying a ground-launched cruise missile with a range of 300 to 3,400 miles.
Mr Trump made the announcement on Saturday following a campaign stop in Elko, Nevada. National Security Adviser John Bolton was on Saturday headed to Russia, Azerbaijan, Armenia and Georgia.
Mr Trump said: "We are going to terminate the agreement and then we are going to develop the weapons" unless Russia and China agree to a new deal.