More than 1,000 Saudi and Gulf states troops marched into Bahrain in March of 2011. The Saudi government was worried about the protest movement spreading into its oil fields and eastern provinces and acted under the terms of a newly-signed treaty by the Gulf states of Saudi Arabia, the United Arab Emirates, Kuwait, Qatar and Oman and Bahrain which pledges the leadership of these countries to act as one against their own citizens in the event of revolutionary upsurges. The Saudi intervention came just two days after U.S. Defense Secretary Robert Gates visited Manama.
Saudi Tanks "Enter" Bahrain to Put Down "Unrest" - Ethan Bronner - NYT March 14, 2011
One suspects that when Soviet tanks "entered" Hungary in 1956
the New York Times had a harsher headline
Cartoon - Saudi tank, Bahraini King - by Carlos Latuff