A year ago, Saudi Arabia went to war with Shia rebels in northern Yemen, who were moving into Saudi Arabia. The Saudis asked the United States for satellite photos of the border area, but the United States refused, for fear of offending Yemen (which never had good relations with the Saudis). Saudi troops pushed the rebels back into Yemen, but had problems tracking the rebels in the mountains along the border. France then stepped up and provided satellite coverage, and suddenly the Saudi bombing missions became much more productive, and fewer civilians were killed.
Saudi participation in the fighting the Yemen rebellion was triggered by an incident on October 14th, 2009, when Saudi police caught two al Qaeda members trying to get past a border post dressed as women, and carrying weapons and bomb making material. The two were killed in a gun battle, along with a policeman. This was but the latest attempt by al Qaeda to use Yemen as a base for attacks inside Saudi Arabia. But this incident was the proverbial last straw.
Thousands of Saudi troops were sent to the border area, where the Yemeni Shia rebels were forced back into Yemen, where they hid among some 60,000 civilian refugees from the fighting. On October 18th, the rebels reported that Saudi troops fired across the border, to support a Yemeni army attack on some rebels barricaded inside a town. Elsewhere on the border, Saudi troops have long been fighting with tribesmen opposed to the security fence the Saudis are building along the border. The tribesmen have freely crossed the border for centuries, but now the Saudis want to halt the smuggling, and movement of al Qaeda terrorists into the kingdom.
After two months of Saudi air and ground operations along the border, many of the rebels retreated to their fortified villages in the mountains. The Yemeni (and sometimes the Saudi) air force bombed these villages, and the Shia rebels complained about civilian casualties. That's usually a sign that the complainers are losing, and striving to make their use of human shields as effective as possible. But not every village was bombed, as that can just bring another clan into the war against the government. So troops, and the French satellites, basically scouted the area constantly, trying to find where the few hundred rebel fighters, from the Houthi tribe are, and attacked or captured them.
The Saudi Air Force heavily patrolled the Yemen border region, hitting rebels (and non-hostile smugglers) caught crossing the semi-desert frontier region. Yemen has had its differences with Saudi Arabia in the past, particularly over the largely unmarked, and disputed, border area. But on the subject of the rebellious Shia tribes of northern Yemen, both nations have quietly agreed to fight as allies to defeat a common threat. Yemen has not complained about the Saudi warships patrolling the north Yemen coast. There, several boats, loaded with weapons for the rebels, have been intercepted. The Shia rebels tried to convince Saudi Arabia to negotiate a peace deal, but the Saudis stood firm with Yemen on this.
The U.S. provided over $200 million in economic and military aid, along with satellite photos and UAVs for aerial surveillance. The Gulf Arabs united behind Yemen, and Saudi Arabia, against Iran (which denied any involvement, despite much evidence to the contrary). The Iranians have to fear that, if the war runs its current course, and some of the rebel leaders are taken alive, it will come out just how involved Iran is. More evidence of Iranian involvement has been found. But before all the rebel leaders could be rounded up, and interrogated, the rebellious tribes made peace last June, and the rebellion died down to a simmer.
Saudi Arabia is shopping for military grade satellite surveillance services, which may be able to obtain from a commercial satellite operator.