Over a thousand military and police personnel from the Gulf Cooperation Council (GCC), the Saudi Arabia-led association of Persian Gulf monarchies, have been sent to Bahrain in an effort to put down the insurrection against the al-Khalifa monarchy.

A Saudi official stated on Monday that around 1,000 of its troops arrived in Bahrain, a tiny island kingdom in the Persian Gulf just a few miles off the eastern coast of Saudi Arabia.

Reuters news agency reported that about 150 Saudi armored troop carriers had been sent to Bahrain. Another GCC member, the United Arab Emirates, announced that it would send police to Bahrain.

Hundreds of thousands of people have demonstrated over several weeks in Bahrain’s capital, Manama, with the largest protests taking place since Friday, when massive crowds marched through the city demanding the fall of the government.

In the most open display of anti-monarchy sentiment yet, tens of thousands of protesters marched to the gates of the Royal Court, the main palace of King Hamad bin Issa al-Khalifa, with many calling for the establishment of a republic.

Witnesses in Manama reported that on Friday Bahraini police fired rubber bullets and teargas grenades into the crowds, while pro-monarchy thugs armed with batons and swords attacked protesters.

News of the GCC intervention has reportedly brought even larger crowds onto the streets of Manama. Tens of thousands of protesters continued to occupy Pearl Square, the focal point of the anti-government demonstrations for weeks, setting up barricades to defend themselves from attack. Bahraini police viciously assaulted protesters in Pearl Square on February 17, wielding clubs and firing shotguns at the peaceful crowd, killing four demonstrators and wounding another 230.

The BBC reported that the Saudi troops had been sent to secure key oil facilities and financial institutions in Bahrain. As Pearl Square is in the middle of Manama’s financial district, it is likely that the GCC intervention will soon face off with demonstrators.

The Bahrain government of King Hamad has not formally confirmed that a GCC intervention is under way, and would only acknowledge that they had requested assistance from the GCC. The monarchy in Bahrain is closely linked to the far more powerful Saudi ruling family. Saudi Arabia sent a military force into Bahrain in 1994 to prop up the al-Khalifa dynasty during the last period of mass demonstrations against its autocratic rule.

While the ruling family in Bahrain is Sunni Muslim, and only Sunnis are permitted to serve in the army and security forces, the majority of the population are Shiites. The anti-government demonstrations are demanding an end to sectarian discrimination, as well as democratic elections and equitable distribution of the country’s oil wealth. However, protesters in Bahrain have called for unity across the religious divide, with placards and chants of, “No Sunni, no Shiite, just Bahraini,” being a feature of the demonstrations since they began in February.

The government, however, is attempting to whip up Sunni sectarian opposition to the protests, with Bahrain’s ambassador to Washington, Houda Ezra Nonoo, describing the events in Manama as “sectarian clashes” between rival Shiite and Sunni gangs.

The Saudi regime and the other monarchies of the GCC fear that the fall of the al-Khalifas will inspire mass protests in their countries. Oman faced large demonstrations earlier in March, which were attacked by police, while Saudi authorities have mobilized thousands of security personnel to clamp down on proposed demonstrations.

The Sunni Muslim sheikdoms of the GCC are also concerned that any accommodation to the Shiite masses in Bahrain will allow pro-Iranian Shiite political parties to increase their power in the strategically important country. Bahrain lies close to Saudi Arabia's main eastern oil producing region, where the majority of the population are Shiites, subjected to discrimination.

The United States is determined to prevent any threat to its interests in Bahrain, which is home to the US Navy’s Fifth Fleet. The base gives Washington military reach in the Persian Gulf and across the Middle East, and is a vital staging post in its occupation of Iraq. Bahrain is also a major oil and natural gas producer, and Washington fears that the spread of the Bahraini protests into Saudi Arabia and the other GCC countries will cause a further increase in oil prices.

The GCC’s military intervention could not have taken place without US sanction. Both the Saudi and the Bahraini monarchies are clients of the United States, which has armed and politically supported the regimes for decades. White House spokesman Tommy Vietor stated on Monday: “We urge our GCC partners to show restraint and respect the rights of the people of Bahrain, and to act in a way that supports dialogue instead of undermining it.”

Washington has been issuing such hypocritical calls for “restraint” for weeks as its allies in Bahrain, Oman, Yemen and Saudi Arabia have repeatedly cracked down on protesters with deadly force.

The Obama administration is pushing for negotiations between the al-Khalifa regime and sections of the bourgeois opposition, in particular the Shiite al-Wefeq party, which functioned as a semi-official opposition in the toothless Bahraini parliament until last month, when it was forced to resign after the regime attacked protesters in Pearl Square.

US Defense Secretary Robert Gates flew into Bahrain on Friday evening, meeting with King Hamad the following day. Gates called for the government in Manama to take “far-reaching steps” towards reform, and praised the king and his son Crown Prince Salman as being “serious about real reform and about moving forward”—even as police were shooting and beating demonstrators.

Gates is concerned that unless the protests can be wound down quickly through talks with the Shiite political parties, the future of the US-backed regime is in doubt. Warning that the Iranian government would seek to profit from the crisis in Bahrain, Gates told the US military newspaper Stars and Stripes that he had warned the king that “time is not our friend.”

“I think what the government needs is for everybody to take a deep breath and provide a little space for this dialogue to go forward,” Gates added.

These statements clearly had the effect of encouraging the al-Khalifas and their Saudi allies to take quick action in a desperate attempt to quell the protests through a show of military force.

However, the intervention of the GCC has made it more difficult for the Shiite parties to maintain negotiations with the government without incurring the opposition of the working class protesters. The National Unity Rally, an umbrella group of opposition parties, issued a statement on Monday opposing the military intervention: “We consider the arrival of any soldier, or military vehicle, into Bahraini territory … an overt occupation of the kingdom of Bahrain and a conspiracy against the unarmed people of Bahrain.”

While Washington may favor some accommodation between the regime in Manama and a section of the Shiite political and clerical elite in Bahrain, the overriding concern of US imperialism is to maintain its foothold in the country, and its domination over the vast energy resources of the region, even if this means an attack on demonstrators by the GCC forces.

As with the Arab League’s March 13 announcement of support for a “no-fly” zone over Libya, which would necessitate an air war against the country by the US and European militaries, the invasion of Bahrain by the GCC demonstrates the complete subordination of the Arab bourgeoisie to imperialism, and their utter hostility to the democratic and social aspirations of the masses. While cynically calling for air strikes against the Gaddafi regime in Libya because of its attacks on anti-government forces, the monarchies of Saudi Arabia and the Gulf simultaneously act to maintain the rule of their fellow despots in Bahrain.