Big US weapons companies have attacked the Senate foreign relations committee for its decision to delay a treaty designed to bolster Anglo-American defence co-operation until the next Congress.

In a letter to Joe Biden, the committee chairman, who is also the Democratic candidate for the vice-presidency, the Aerospace Industries Association (AIA) said failure to approve the treaty this year “would be an unfortunate setback in ongoing efforts to shape an export control regime that will serve America’s interests in the 21st century”.