Schwarzenegger on US troops guarding Mexico border

California's Governor Arnold Schwarzenegger has stressed the importance of border control with neighbour Mexico after deploying US National Guard troops to protect the divide.

200 military personnel from California have been sent to its southern border with Mexico, the first of up to 1,200 National Guard Troops who will support existing agents in the four US states along the country's southwestern frontier.

Arnold Schwarzenegger said the troops had been called to help protect the safety of the American people.

There are an estimated 12 million people in the US illegally, most having crossed the southern border from Mexico.