WEST POINT, N.Y. – President Barack Obama ordered an additional 30,000 U.S. troops into the long war in Afghanistan on Tuesday night, and told an impatient American public he hopes a gradual withdrawal can begin within 18 months.

In a prime-time address from the U.S. Military Academy, the president said the additional forces would be deployed at "the fastest pace possible so that they can target the insurgency and secure key population centers." Excerpts of his remarks were released in advance...