About 2,000 foreign troops, led by Saudi Arabia, rolled into Bahrain Monday, threatening to turn the unrest in the tiny kingdom into a regional showdown with Iran. Saudi Arabia has been watching the Bahraini protests carefully, wary that a victory for the protesters could result in a greater Iranian presence—especially since Iran has long contended that Bahrain is historically a part of Iran. Saudi Arabia sent 1,200 troops and United Arab Emirates sent 800 as part of the Gulf Cooperation Council, a six-nation regional coalition of Sunni rulers. The troops arrived at particularly pivotal moment of the revolt, as protesters have moved from Pearl Square—the symbolic center of the nation—to the Royal Court and the financial district where the power and influence really is located. Given the United States’ strong alliance with the Bahraini royal family, a Saudi official said Monday that the U.S. was aware the Saudi troops were going in.