President Trump’s plan to divert military construction money to fund a border wall is an unusual use of emergency powers. Just once in the last four decades has an emergency declaration authorized military action: in 2001, after the Sept. 11 terrorist attacks. (Some declarations were subsequently amended to include a call for military action.)

National Emergency Declarations Since 1976 sanctions trade regulations weapons restrictions other military action

Presidents typically invoke emergency powers to impose sanctions on foreign individuals, groups or nations that threaten national security, though they have also been used domestically amid public health crises and to regulate exports.

Since the National Emergencies Act was passed in 1976, seven presidents have declared dozens of national emergencies, and 32 are still active.