Yemeni police firing from rooftops wounded more than 100 in a protesters' camp Sunday and anti-government demonstrators paralyzed Bahrain's capital as unrest deepened in two of Washington's most critical allies in the region.
The ruler of Oman, another key Western partner, shifted some lawmaking powers to officials outside the royal family in what an analyst called a historic change.
Meanwhile, Saudi authorities tolerated 200 activists demanding the release of detainees in defiance of stern warnings of crackdowns on pro-democracy rallies.
The range of responses _ from attacks to appeasement _ underscored the different gambits at play. Some regimes are looking to battle their way out while others turn to rapid reforms in a bid to quell dissent inspired by groundswell for change across the Arab world.
Yemen's president, Ali Abdullah Saleh, has increasingly turned to confrontation after protesters rebuffed his offer to bow out with elections in 2013.
Near Sanaa University, an encampment of demonstrators came under twin attacks: police firing from rooftop positions, and a ground assault by security forces and government backers armed with clubs and knives. Mohammad al-Abahi, a doctor in charge of a makeshift hospital near the university, said more than 100 people were injured, including 20 from tear gas inhalation.
In the southern Aden province, it was the protesters on the offensive _ storming a police station and seizing weapons after police fled, witnesses said.
Yemen _ hit by a wave of protests since mid-February _ is considered by Washington to be a vital front-line ally against one of the world's most active al-Qaida branches. But the U.S. patience for Saleh's tactics appears to be wearing thin.
Bahrain's showdown also has reached the one-month mark with no end in sight. There are now fears the tiny kingdom could be stumbling toward open sectarian conflict between the ruling minority Sunnis and Shiites, who account for 70 percent of the nation's 525,000 people.
The mostly Shiite protesters first took to the streets to air their allegations of widespread discrimination. But the calls have been growing to topple the entire ruling monarchy after attacks and crackdowns by security forces in the strategic nation, which hosts the U.S. Navy's 5th Fleet.
Protesters displayed their power with a new and disruptive strategy _ blocking the main highway into the financial district in the capital Manama, one of the Gulf's investment and banking centers. Riot police firing tear gas eventually cleared the barricades, but traffic was snarled for miles (kilometers) and morning commuters were enraged.
"Bahrain is no longer stable," growled Sawsan Mohammed, 30, who works in the financial district.
In some neighborhoods, vigilantes set up checkpoints to try to keep outsiders from entering. Some Shiite protesters claimed that pro-government gangs were roaming some areas armed with clubs and other weapons.
At Bahrain University, clashes broke out between protesters and government backers. Two protesters sustained serious head injures and hundreds looked for medical help, mostly with breathing problems from tear gas, hospital officials said on condition of anonymity because they were not authorized to speak to the media.
In Pearl Square _ a landmark site occupied by demonstrators _ security forces surrounded the tent compound, shooting tear gas in the largest effort to disrupt the protesters since a crackdown last month left four dead.
Police withdrew after activists stood their ground and chanted "Peaceful! peaceful!"
The turmoil came a day after a visit by U.S. Defense Secretary Robert Gates, who urged Bahrain's leaders to make quick progress toward reforms. Washington and its Gulf Arab allies worry that Shiite powerhouse Iran could use instability in Bahrain as a foothold to expand its influence in the region.
In Oman _ a close ally of both the U.S. and Iran _ the ruler Sultan Qaboos bin Said issued a decree saying he would hand legislative and regulatory powers within 30 days to two current advisory councils, one elected and another appointed by the sultan.
The move reflects the scramble to head off possible wider unrest in the strategically important nation. Oman and Iran share control of the Strait of Hormuz at the mouth of the Gulf, which carries 40 percent of the world's oil tanker traffic.
Just hours before the announcement, suspected arsonists burned a government office and the home of a clan leader in Ebri, about 210 miles (350 kilometers) northwest of the capital Muscat. No injuries were reported, but military units boosted their presence in the area.
The sultan has made sweeping Cabinet shake-ups and promises for thousands of new civil service posts since demonstrations began late last month. But the latest plan introduces the most fundamental changes about how the country is governed.
An Oman-based political analyst, Saeed Awad bin Bagoer, described the sultan's plan to transfer powers to the council as an "historic political reform."
In the Saudi capital Riyadh, more than 200 people were allowed to protest outside the Interior Ministry to demand the release of detainees held on security and terrorism-related charges.
The rally was held despite a ban on demonstrations and threats for harsh crackdowns on any challenge to the pro-Western monarchy. It was not clear whether it was a bid by Saudi authorities to allow limited demonstrations or if the protesters could face punishment later.
Moroccan police broke up an unauthorized protest in Casablanca by several hundred people, including many supporters of Morocco's best-known Islamist movement, the Justice and Spirituality movement.
An Interior Ministry official told The Associated Press that about 50 protesters were arrested and four officers injured.
King Mohammed VI said Wednesday that Morocco will revise its constitution for the first time in 15 years _ part of steps to build greater democracy.
Associated Press writers Ahmed Al-Haj in Sanaa, Yemen; Reem Khalifa in Manama, Bahrain, and Saeed Al-Nahdy in Muscat, Oman, contributed to this report.