As it was during the early days of the mass antigovernment uprising in Egypt, the United States finds itself in a tricky position regarding Bahrain.

Just two months ago, Secretary of State Hillary Clinton pronounced herself “very impressed by the progress that Bahrain is making on all fronts – economically, politically, socially.”

“There seems to be a strong broadly-held commitment to democracy,” she said at a town hall meeting in Manama, Bahrain’s capital and largest city.

Bahrain protests: Five key facts

That was before pro-democracy demonstrators filled the streets and government forces responded with deadly force, killing at least four people and sending dozens to hospitals. (Thousands of protesters demanding political and social reforms gathered again Saturday, although security forces let them do so without reacting.)

For years, the US has considered Bahrain an important ally in the region. As with Egypt, the US has sold advanced military equipment to the kingdom – including fighter aircraft, attack helicopters, and battle tanks (some of which were used to confront demonstrators). Last year, the US provided around $20 million in military aid to Bahrain.

Perhaps more critical, Bahrain also is the homeport for the US Fifth Fleet.

From there, US warships and contingents of US Marines can keep an eye on – and, if necessary, rattle sabers – close to oil shipping lanes, Iran, and the increasing activity of pirates. (It was reported Saturday that an ocean-going sailboat with four Americans aboard had been hijacked by pirates.)

With about 30 ships (including two aircraft carriers) the Fifth Fleet patrols the Persian Gulf, the Red Sea, the Arabian Sea, and the east coast of Africa.

In a post 9/11 world, the US fleet plays a role similar to the US Navy’s outpost in Subic Bay in the Philippines during the Vietnam War. It’s a critical staging area for combat (or in this case, the possibility of combat) in an area perceived to be crucial to US interests. But instead of toppling dominoes in Southeast Asia, it’s a major regional supplier of oil and the threat of Islamic terrorism.

Bahrain has provided basing and overflight clearances for US aircraft engaged in Afghanistan, and it has helped cut off money supplies to suspected Islamic terrorists. More than 4,000 US service personnel live and move about freely there.

"Could we find some other place to put a fleet headquarters? Probably we could," Anthony Cordesman, a defense analyst at the Center for Strategic and International Studies, told the Wall Street Journal. "But if Bahrain becomes unstable, if it comes under Iranian influence … [that] threatens the entire structure of world oil markets."

For now, US officials are responding to the demonstrations and violence in Bahrain much as they initially did in Egypt.

Secretary Clinton and Defense Secretary Robert Gates have called their counterparts in Bahrain. President Obama called Bahrain’s King Hamad bin Isa Al-Khalifa.

“People have certain universal rights including the right to peaceful assembly,” the White House said in a statement Friday. “The United States urges the governments of Bahrain, Libya and Yemen to show restraint in responding to peaceful protests, and to respect the rights of their people.”

Bahrain protests: Five key facts