A Defense Department spokesman said the security agreement between US and Iraq provided both the time and authority needed for American troops to train Iraqi forces and go after terrorists. Press secretary Geoff Morrell spoke as Defense Secretary Robert Gates and Secretary of State Condoleezza Rice headed to Congress on Wednesday to explain and defend the agreement before lawmakers. The pact, being debated by Iraqi officials, lays out US troop withdrawal timelines and gives Iraq limited legal jurisdiction over US forces and contractors who commit crimes. Morrell said defense officials believe that security has improved such that, if trends continue, the US will not be needed in Iraq in 2012. The agreement calls for US combat forces to leave the cities by next June, and all of Iraq by the end of 2011.