The deployment has been criticized by local officials as an infringement of their city’s autonomy and by Democrats who say it has militarized the streets at the public’s expense.

The cost estimate was provided to Sen. Elizabeth Warren (D-MA), a member of the Senate Armed Services Committee.

The extension of the National Guard deployment in Washington, D.C. until January 2029 will cost roughly $1.4 billion, according to a Defense Department estimate provided to…