The Obama and Bush teams have been working together throughout the President-elect's transition to power.
Tuesday, that continued with the first ever joint-administration White House "war games."
It involved mock disasters, both natural and terrorist-related, to practice how the government would respond.
The drills took place in the White House situation room and were orchestrated by the Department of Homeland Security.
Obama's incoming chief of staff said the unprecedented joint exercise was important during a war-time transition.
"We all in the end of the day work for the American people," Rahm Emanuel said. "Whether we are Democrats or Republicans we will have our policy differences, but there is no policy difference when it comes to protecting the American people."
President Bush's chief of staff Josh Bolten recommended the joint war games to help ensure a seamless hand-off to the next administration.