(AP) - President Barack Obama on Friday ordered 4,000more military troops into Afghanistan, vowing to "disrupt,dismantle and defeat" the Taliban and al-Qaida. The new troop build up he announced is aimed principally atbolstering the Afghan army and turning up the heat on terroriststhat Obama said are plotting new attacks against Americans. He called the situation in the region "increasingly perilous"more than seven years after the Taliban was removed from power inAfghanistan. "If the Afghanistan government falls to the Taliban or allowsal-Qaida to go unchallenged," Obama said, "that country willagain be a base for terrorists." He announced the troop deployment, as well as plans to sendhundreds of additional civilians to Afghanistan, with Secretary ofState Hillary Rodham Clinton, Defense Secretary Robert Gates andtop intelligence and national security figures at his side. Theannouncement came at the end of an extensive policy review thatObama launched on Afghan-Pakistan policy not long after taking theoath of office. The 4,000 troops come not long after the new administrationapproved the dispatch of an additional 17,000 forces to thewar-weary nation. Obama bluntly warned that the al-Qaida terrorists whomasterminded the Sept. 11, 2001 attacks were actively planningfurther attacks on the United States from safe havens in Pakistan.And he said the Afghanistan government is in peril of falling tothe Islamic militants of the Taliban once again.