President Barack Obama spoke with Bahrain's king on Friday night, urging restraint after the kingdom's security forces ignored Washington's earlier call for calm and opened fire on protesters demanding reforms.
Amid unrest across much of the Middle East, US officials have voiced concern about violence in the island nation in talks with the government of Bahrain, which hosts a big US military base and borders Saudi Arabia, the world's largest oil exporter.
The White House said in a statement that Obama, in speaking with King Hamad bin Isa Al-Khalifa, condemned violence and said Bahrain's stability depended on respect for the rights of its people.
Earlier on Friday, Obama said he was deeply concerned by reports of violence in Bahrain, Libya and Yemen. "The United States condemns the use of violence by governments against peaceful protesters in those countries, and wherever else it may occur," Obama said in a statement.
Democratic Senator Patrick Leahy said he had asked the State Department to probe whether Bahrain had broken a US law he wrote that prohibits aid to foreign security forces that violate human rights. The United States provided around $20 million in military aid to Bahrain in 2010.
Bahraini security forces shot at protesters in the capital, Manama, on Friday, wounding at least 60 people, a day after police swept away a protest camp in the city, killing four people and wounding more than 230.
In Libya, soldiers sought to crush unrest. In Yemen, at least four protesters were killed in clashes between security forces and government loyalists and crowds demanding an end to President Ali Abdullah Saleh's 32-year rule.
Bahrain's crackdown on protesters posed a new dilemma for the Obama administration after a popular uprising in Egypt ousted US ally President Hosni Mubarak a week ago.
A US national security official said Bahrain security forces appeared to be using rubber bullets and live ammunition fired from, but not limited to, shotguns.
"˜Want to avoid'
"This (violence) is exactly what the administration and the US want to avoid," said Robert Danin, a Middle East expert at the Council on Foreign Relations think tank.
"In the case of Egypt, the goal was to see managed change, (an) orderly transition. But the number-one thing was to ensure that this be done without violence. The minute that there's violence it is very hard to reconcile support for your ally and the aspirations of the demonstrators."
US national security and intelligence agencies expect Bahrain's government to ride out the unrest and that security forces will eventually succeed in containing the protests, a senior US official familiar with government reporting and analysis on Bahrain told Reuters.
The United States views Bahrain, home to the US Navy's Fifth Fleet, as a strategic ally that straddles oil supply lines in the Gulf. As in the case of Egypt and elsewhere in the region, it must balance strategic interests with its support for protesters' demands for economic and political reforms.
Obama's response may be colored by the US view of Bahrain as one of the more progressive Arab states. Secretary of State Hillary Clinton told Bahrain civil society activists during a visit in December their government was moving more quickly than many others in the region to implement democratic change.
Several 2009 cables from the US Embassy in Manama, made available to Reuters, characterized King Hamad as an enlightened and deeply pro-American ruler who, since assuming the throne in 1999, had fostered reconciliation with the Shi'ite Muslim majority and had undertaken serious political and economic reforms.
"The US is in a rather embarrassing position, because officials have tended to give King Hamad far more credit than they should have for political reforms," said Michele Dunne, a Middle East expert at the Carnegie Endowment for International Peace.
The State Department issued a travel warning on Friday for Bahrain, noting clashes between protesters and demonstrators. "Spontaneous demonstrations and violence are expected throughout the next several days," the department said, urging US citizens to defer nonessential travel to the country.
Middle East experts said the Obama administration had little leverage over Bahrain's Sunni Muslim monarchy.
Admiral Mike Mullen, the top US military officer, may be reprising the role he played in the Egypt uprising by keeping channels open to the Bahraini military, they said.
"The options to bring pressure seem extremely limited. Despite the close alliance, Bahrain has been defiant of the United States over the years," said Simon Henderson, a Gulf expert at the Washington Institute for Near East Policy.