Philando Castile's girlfriend says his weapon was concealed when a cop fatally shot him.
The police chief again defended the decision to kill the suspect with a bomb delivered by a robot.
The additional forces will be sent to establish an air base for the long-awaited battle to recapture Mosul from the militant group.
David Cameron's last day as prime minster will be Wednesday, and Theresa May will take office shortly thereafter.
The presumptive GOP nominee started his first public event since the Dallas shootings with a lengthy statement.