The United States is to accelerate its development of new cruise and ballistic missile systems following its withdrawal from a nuclear treaty with Russia, the Pentagon said on Friday.

Accusing Russia of "sustained and repeated violations" of the Intermediate-Range Nuclear Forces (INF) treaty, Defence Secretary Mark Esper said the US had already begun work to develop "mobile, conventional, ground-launched cruise and ballistic missile systems."

As the United States had "scrupulously complied" with its obligations to the 1987 treaty until its formal withdrawal, "these programs are in the early stages," Esper said in a statement. 

"Now that we have withdrawn, the Department of Defense will fully pursue the development of these ground-launched conventional missiles as a prudent response to Russia's actions.

"The Department of Defence will work closely with our allies as we move forward in implementing the National Defence Strategy, protecting our national defence and building partner capacity," he added.

Moscow has said that Washington is making a "serious mistake" pulling out of the treaty, insisting that the US had abandoned the agreement for its own gain rather than because of alleged Russian violations.