Bahraini protesters poured back to the streets Wednesday after a security court sentenced eight Shiite activists to life in prison in the latest blow by the Western-backed kingdom to cripple the biggest Arab Spring opposition movement in the Gulf.
The fast and angry reaction to the verdicts _ the most significant display of unrest in weeks _ underscored the volatility in the island nation after four months of unrest and raised questions about whether any credible pro-reform leaders will heed calls by the Sunni monarchy to open talks next week.
In size, Bahrain is little more than a speck off the coast of Saudi Arabia. But it draws in some of the region's major players: hosting the U.S. Navy's 5th Fleet and serving as a growing point of friction between Gulf powers Saudi Arabia and Iran.
Security forces used tear gas to drive back hundreds of Shiite marchers trying to reach a central square in the capital Manama, which was once the hub of their protests for greater rights. In other Shiite areas, protesters gathered in the streets but were held back by riot police. No injuries were reported.
Bahrain has allowed two major rallies this month by the main opposition party, but the confrontations Wednesday were among the biggest challenges to security forces since martial law-style rule was lifted June 1.
Shiites account for 70 percent of Bahrain's population of some 525,000, but claim they face systematic discrimination such as being barred from top government and political posts.
The protests _ claiming at least 31 lives since February _ have put U.S. officials in the difficult position of both denouncing the violence and standing by Bahrain's rulers and their call for dialogue. In response, opposition groups have increased demands that include an end to the political trials and withdrawal of a Saudi-led regional force helping prop up Bahrain's ruling family.
In Washington, State Department spokesman Mark Toner said the U.S. was "concerned about the severity" of the sentences and the use of the military-linked security courts. He noted that President Barack Obama said in May that "such steps are at odds with the universal rights of Bahrain's citizens."
"We continue to urge the Bahraini government to abide by its commitment to transparent judicial proceedings, conducted in full accordance with Bahrain's international legal obligations, and to create the conditions for a meaningful, inclusive and credible dialogue," he said.
Bahrain's government said in statement late Wednesday that the convicted activists were responsible for "bringing the country to the brink of total anarchy" with a wave of marches and sit-ins earlier this year.
"Today's sentencing sends a message that law and order will be preserved," the statement said, pledging to guard against "attempts to overthrow the regime."
The official Bahrain News Agency said those sentenced to life include prominent Shiite political figures Hassan Mushaima and Abdul Jalil al-Singace and rights activist Abdulhadi al-Khawaja. Mushaima returned from self-exile in London earlier this year after Bahrain's leaders promised to erase old charges of opposing the state.
Pro-reform activist Ibrahim Sharif _ the only Sunni among the suspects _ received five years in prison, while other sentences ranged from two to 15 years. The sentences can be appealed.
A leading opposition figure cast doubt on whether talks can get under way.
"We should conduct the dialogue in an open atmosphere, not when people are being arrested," said Khalil al-Marzooq, who was among the 18 Shiite parliament members who staged a mass resignation to protest the crackdowns earlier this year.
The charges at the latest security court trial show the depths of the tensions. The activists were convicted of trying to overthrow Bahrain's 200-year-old monarchy and having links to "a terrorist organization abroad" _ an obvious reference to claims that Iranian-backed Hezbollah is behind the unrest.
Eight received life sentences while 13 others received shorter prison terms apparently because they weren't considered leaders.
Bahrain's rulers fear that any Shiite gains in the country could open new footholds for influence by Shiite power Iran.
Shiite leaders in Bahrain repeatedly have denied any ties to Iran and accuse leaders of using the fears of Iranian string-pulling to wage crackdowns that have included hundreds of arrests and purges from jobs and universities.
Fourteen of the 21 convicted are in custody while the rest were sentenced in absentia by the security court, which uses military prosecutors and a military-civilian tribunal. Among the life sentences, however, all but one of the suspects was in Bahrain.
Sharif's wife, Farida Ghulam, said her husband cried out "Our people demand freedom" after the sentences were read.
Ghulam said al-Khawaja then shouted: "We will continue our struggle." His daughter, Zainab, was dragged from court by female guards after she yelled "Allahu akbar," or "God is great," said Ghulam.
The verdicts could also bring some direct diplomatic fallout. At least two of those sentenced to life also hold European passports: al-Khawaja, who is a Danish citizen, and Mohammed Habib al-Muqdad, who has Swedish citizenship.
The court has presided over a series of cases linked to the protests, including issuing two death sentences against men accused of killing police officers during the demonstrations. Earlier this month, it sentenced a 20-year-old woman to a year in prison for reading poetry critical of Bahrain's king.
Next week, a trial is scheduled to resume for more than 30 doctors and nurses accused of supporting the protests. Some of the medical personnel claim they were abused while in custody.
Associated Press writers Matthew Lee in Washington and Barbara Surk in Dubai contributed to this report.