Over the last month, the Shiite protests against Bahrain's Sunni monarchy have produced flashes of violence but no systematic government crackdown.That changed on Wednesday, when Bahraini security forces, supported by tanks, helicopters, and armored jeeps, fired tear gas at protesters and drove them out of their headquarters in Manama's Pearl Roundabout. Three policemen and three demonstrators were killed in the clash, the Associated Press reports.

The violence comes a day after Bahrain's king declared martial law in the country. A legislator from Bahrain's largest Shiite opposition party called the monarchy's actions a "war of  annihilation," according to Reuters.

Critically, the unrest in Bahrain has morphed into a regional conflict, with the Gulf Cooperation Council (GCC) sending forces to help Bahrain's monarchy maintain order and Shiite-ruled, non-Arab Iran denouncing the arrival of GCC troops from Sunni-ruled Arab countries like Saudi Arabia. In Iraq, Shiite cleric Moqtada al-Sadr called for mass demonstrations in solidarity with Bahrain's protesters.

America is also in a tough spot. Bahrain and Saudi Arabia are long-time allies and, as the AP and Reuters note, the Navy's Fifth Fleet in Bahrain serves as a check on Iran's military ambitions while Saudi Arabia provides the U.S. with 12 percent of its oil imports and acts as a counterweight to Iran. The U.S. has urged the Bahraini monarch to show restraint and dispatched a State Department official to the island to facilitate negotiations. Already, escalating tensions in Bahrain have sent oil prices rising amidst concern that unrest could spread to neighboring Saudi Arabia.

What's next in Bahrain? The youth movement has called for a march on Wednesday from Manama's suburbs toward the capital along the Budaiya highway. Reuters is reporting that soldiers and tanks are moving towards the highway, paving the way for what could be another violent confrontation.

Update

Some graphic videos are now surfacing that allegedly depict the violence in Bahrain on Wednesday. In this clip highlighted by Business Insider, Bahraini police appear to wrestle a protester to the ground and shoot him several times before leaving the scene, as the man struggles to get up.

In another, police beat a man before shoving him into their car.