Planning for the museum in Belvoir, Virginia, has been in the works for more than a decade.

The 20-year-old man, armed with an automatic rifle and a fake explosive vest, fatally shot four people before he was killed by police.

Their aim, they say, is to ‘reclaim the public space from criminal elements masquerading as protesters’ after days of demonstrations over police abuses that left 69 people dead.

The Labor Day tragedy last year was one of the deadliest accidents in recent U.S. maritime history.

The agreement is a bid to salvage their last remaining arms control pact before it expires next year.