[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/POLITICS/03/26/us.afghanistan.troops/art.obama.townhall.cnn.jpg caption=" President Obama is expected to announce new strategies for Afghanistan and Pakistan on Friday."]WASHINGTON (CNN) - President Obama plans to send another 4,000 troops to Afghanistan along with hundreds of civilian specialists in an effort to confront what he considers "the central challenge facing [that] country," senior administration officials said Thursday.
The president also will call on Congress to pass a bill that triples U.S. aid to Pakistan to $1.5 billion a year over five years, the officials said.
Obama is expected to announce new strategies for both countries Friday.
The troops, which are in addition to the 17,000 the president announced earlier would be sent to Afghanistan, will be charged with training and building the Afghan army and police force. The plans include doubling the army's ranks to 135,000 and the police force to 80,000 by 2011, the officials said.
Listen: CNN Deputy Political Director Paul Steinhauser discusses the politics of the president's new plan with CNN Radio's Bill Caiaccio