At least 46 workers were killed and scores more wounded in Sanaa, the capital of Yemen, when security forces opened fire on a march of tens of thousands demanding an end to the dictatorial regime of President Ali Abdullah Saleh.

The event exposes the staggering hypocrisy of the US and its imperialist allies, who are now preparing to bombard Libya in the name of protecting its people from the Gaddafi government. The US has meanwhile tacitly encouraged its stooge Saleh to snuff out working class opposition because of Yemen’s critical location near the oilfields of Saudi Arabia and the sea lanes connecting the Red Sea to the Indian Ocean.

In the aftermath of the massacre, President Obama issued a statement calling on “all sides” to follow “a peaceful, orderly and democratic path to a stronger and more prosperous nation.” The statement amounted to a stamp of approval for the mass killing.

Friday’s massacre marked the bloodiest day in the one-month-old uprising of workers, tribesmen and youth. The march, which was called to mourn the killing of seven protesters at the hands of the regime last week, stretched for more than a mile along a road near Sanaa University.

Security forces in the front of the march opened fire on the unarmed demonstrators as they rose from their knees after morning prayers. Simultaneously plainclothes policemen began to fire on the demonstration from the rooftops of nearby buildings.

“As soon as we got up from prayer they started firing from the tops of multiple buildings in the area,” Essam al-Maqtary, a Sanaa resident shot in the leg, told a Western reporter. “The baltageya [thugs] lit tires on fire so nobody could see exactly where they were and so they couldn’t be recorded on video.”

Hundreds of wounded and dying demonstrators were transported to a nearby mosque. Injuries to the dead and wounded revealed many gunshot wounds in the head, neck, and chest. Saleh’s forces were shooting to kill.

“They shot people in the back of the head as they were running away,” Mohammed al-Jamil, an Indian doctor treating the wounded, told the Guardian. “Whoever did this wanted these people to die.”

After the massacre, Saleh imposed a state of emergency and a nationwide curfew.

In a testament to the determination of the Yemeni workers and youth, the massacre failed to break up the demonstration, which continued to swell and push toward the city center. Later in the day, protesters began to chase armed gunmen. Bystanders tossed onions down to demonstrators to help them deal with the effects of tear gas.

“Though many in the crowd ran for cover when the shooting started, a crowd of mostly tribal men from the outskirts of the capital appeared to stand firm,” reported New York Times correspondent Laura Kasinoff from Sanaa. “A man walked through the crowd with a microphone yelling, ‘Peaceful, peaceful! Don’t be afraid of the bullets!’ ”

“I actually expect more than this, because freedom requires martyrs,” said an unemployed tribesman from outside Sana named Abdul-Ghani Soliman. “This will continue, and it will grow.”

Demonstrators raided the buildings where gunmen were hiding, capturing and beating several. In at least one case, they detained a man with military identification.

Other demonstrations took place after Friday prayers in the cities of Aden, Amran, Hodeidah, Ibb, and Taiz.

A Western journalist in Sana, Erik Stier of the Christian Science Monitor, reports that the demonstrations have become progressively larger, and that the proportional size of the working class component, as compared to the students, has grown. A similar development occurred in Egypt in the days leading up to the collapse of the Mubarak regime. In Libya, by contrast, the “opposition” appears to have been constricted to a relatively small number of tribal elites and former Gaddafi associates.

“As violence has increased in frequency in recent weeks, the opposition crowd at the university has evolved in response,” Stier notes. “Thousands of tribesmen coming from Yemen’s mountainous regions to the north and east have joined calls for the fall of Mr. Saleh’s regime. They now appear to make up at least half of the opposition demonstrators.”

At least 90 demonstrators have been killed in Saleh’s bid to stay in power, though the true figure is certainly far higher. Thousands more have been injured or arrested.

The massacre in Yemen follows a similar assault on demonstrators in Bahrain only two days ago, in which at least seven were killed. Taken together, the two events suggest a degree of coordination, likely involving the peninsula’s major power Saudi Arabia, which sent heavily armed military forces into Bahrain on Tuesday.

Such maneuvers could not be possible without the advanced knowledge of the US, whose intelligence agencies and military are closely integrated with all three regimes. With the attention of the world gripped by the disaster in Japan and the impending military actions against Libya, it can only be concluded that the Obama administration has given a green light to the bloody crackdowns in the Arabian Peninsula.

The sheer brutality of Saleh’s attack on peaceful demonstrators at least matches any single effort by the Gaddafi regime to crush protests in Libya. Yet there have been no calls from the imperialist powers or the Arab League for punitive action against Saleh, who has ruled the Arab world’s most impoverished country for 32 years.

In his Friday statement, Obama limply called on Saleh “to adhere to his public pledge to allow demonstrations to take place peacefully.” A statement issued from Secretary of State Hillary Clinton also stopped short of condemning the murderous assault by the Saleh regime. “With regard to Yemen, our message remains the same,” she said. “The violence needs to end, negotiations need to be pursued in order to reach a political solution.”

United Nations Secretary-General Ban Ki-moon issued a statement saying he was “deeply troubled” by the violence and calling on “all to desist from any provocative acts that might lead to further violence,” implicitly placing half of the blame on the demonstrators.

The Arab League has revealed itself to be a tool of imperialism. In the case of Libya, its demand for the imposition of a no-fly zone has provided the US, France and Britain their most important pretext for bombing the North African country.

In the case of Yemen and Bahrain, however, the Arab League has made no such call for foreign intervention.

“What is happening in Yemen is extremely disturbing and it is a source of deep concern,” Hissam Youssef, the chief of staff of the Arab League’s secretary-general, told Al Jazeera. “We have asked for dialogue, we have asked for responding positively to the demands and concerns of the people, and we are continuing our consultations in this regard.” This comment was notable for stopping short of even a call for restraint.