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5:07 ET: First King Abdullah stomped out the protests in Saudi Arabia. Now he has sent troops to Bahrain to keep protesters out of the region.

Bahraini newspaper Akhbar Al Khaleej says 1,000 Saudi troops have arrived to protect oil, power facilities and banking center -- reported also by Bahrain State TV and Al-Watan. UAE forces are also expected to arrive today.

Bahrain put the call out yesterday after protesters blockaded the financial district in some of the largest unrest yet, according to the FT.

Saudi Arabia and UAE have far more oil money than Bahrain, and Saudia Arabia in particular has a powerful US-backed military.

8:29 ET: Bahrain's Shiite opposition says any intervention by Gulf Arab forces is a declaration of war and occupation, according to Reuters.

9:54 ET: 200 Saudi military vehicles are heading for the government center at Rifa, according to Al Manar. Meanwhile thousands of protesters are headed for Pearl Square.

11:30 ET: Now there are various videos of the Saudi vehicles entering Bahrain.

This video, uploaded to Youtube by ILoveKingHamad, shows the Saudis entering triumphantly as passersby cheer:

Here's another video of tanks lined at the border: