President Barack Obama on Friday said hackers had infiltrated his campaign’s computer systems between August and October 2008, forcing the campaign to call in law enforcement officials and computer experts to remedy the problem. Obama, who spoke at the White House as he announced a new cyber czar to oversee the government’s cybersecurity efforts, did not say whether his campaign had figured out who did the hacking or whether the hackers were caught.But reports surfaced around Election Day that Obama and Sen. John McCain’s (R-Ariz.) campaigns had been hacked by a foreign entity and that the Chinese had gained access to the White House computer system.Obama said the new cybersecurity chief, who will report directly to him, will be part of a government-wide effort to focus on a threat that he said jeopardizes the economy, public safety and national security. Obama did not name a person to fill the position, which will be part of the national security staff and the White House National Economic Council.“We’re not as prepared as we should be,— said Obama, who noted that al-Qaida was not only hoping to inflict violent attacks, but to launch a computer assault as well. With a few “key strokes on the computer,— al-Qaida could inflict a “weapon of mass disruption,— Obama said.