When Governor Arnold Schwarzenegger announced this afternoon that he has agreed to send 1000 of the state's National Guard troops to the Mexico border, it was clear that he-- and not the federal government-- will retain the authority to decide what those troops will do, and how long they will do it.

The governor told Capitol reporters this afternoon that he will sign a memorandum of understanding with federal officials in support of President Bush's call for Guard troops to assist agents of the U.S. Border Patrol. Since the President's announcement two weeks ago, Schwarzenegger and California National Guard leaders have huddled to figure out exactly how to make it work.

The assignment, though, is still not official: the governor's aides say he has not yet signed the documents or given any official Guard orders, as the final details are still being sorted out.

And while he said the mission will end no later than December 31, 2008, it sounded as though it could end sooner, if he doesn't like the way the state's troops are being used.

"I'm the commander-in-chief," he said, "so I can take back the National Guard at any time that I want."

Schwarzenegger said he has also been assured by the White House that the feds will, in fact, pick up the tab for the mission. The cost for the California portion of the assignment alone: $6-8 million per month, according to Guard officers who briefed reporters this afternoon.

As for mission duties, the governor confirmed it will be only to support Border Patrol agents-- not to conduct actual law enforcement activities. "We do not want to militarize the border zone," he said.

Other details: the deployment is scheduled to begin July 15... the National Guard will ask for volunteers, who will serve tours that are likely between 6 months and 1 year... the agreement with the federal government will be signed by Deputy Defense Secretary Gordon England... and while unlikely, it is possible that California troops could be deployed to one of the three other border states if their skills are needed there.