The White House on Tuesday hailed the announcement of the military that its troops have dropped to below 50,000 in Iraq, announcing President Barack Obama will make a speech next week to mark the change of mission in Iraq at the end of the month.

John Brennan, assistant to the president for counterterrorism and homeland security, told reporters at a news briefing conducted at Martha's Vineyard, Massachusetts, where Obama has been vacationing, that the development reaches the goal set by Obama as part of his efforts to draw down forces from Iraq.

"After September 1st, the United States will have a different mission, one of advising and assisting Iraqi security forces, joining the Iraqis in targeted counterterrorism operations and protecting U.S. troops and civilians who remain in Iraq," said Brennan.

White House spokesman Bill Burton said Obama will be making a major speech on Aug. 31 on "the importance of the milepost" as U.S. military changes its missions in Iraq. The New York Times first reported the speech.

The U.S. military on Tuesday said its troops have dropped to below 50,000 in Iraq ahead of the Aug. 31 deadline to end combat operations. After the deadline, Washington said about 50,000 U.S. troops will remain in Iraq to conduct support and training missions.