Talks between the government of Yemen and opposition parties broke down on Sunday amid ongoing deadly clashes across the country and a campaign of aerial bombardment by US forces.

Interim government head Vice President Abd al-Rab Mansur al-Hadi reportedly refused to meet with the opposition leaders on the grounds that the regime was preoccupied with its attempts to suppress tribal insurgencies outside the capital, Sanaa.

Yemen’s president, Ali Abdullah Saleh, was forced to leave the country for medical treatment in Saudi Arabia June 9 after a bomb blast in the presidential compound left him severely injured. Saleh handed over temporary control of the government to his long-term vice president, al-Hadi.

Following the rejection of dialogue by the government, opposition spokesman Mohammed al-Mutawakkil stated, “The American and European efforts for a dialogue between opposition parties and the ruling party have failed.”

The proposed negotiations between the vice president and leading figures from the main bourgeois opposition group, the Joint Meeting Parties, were aimed at shutting down the huge street protests that have taken place in the capital, Sanaa, and other cities across Yemen over the past six months.

The mass protests have seen hundreds of thousand of workers and youth take to the streets, animated not only by hatred for the authoritarian regime in Sanaa but by opposition to the conditions of poverty and mass unemployment faced by most Yemenis. The country is the poorest in the Arab world, with around half the population living on less than $2 per day.

Washington and the European Union have urged Saleh, who has ruled Yemen for 33 years, to accept an agreement brokered by the Saudi-led Gulf Cooperation Council that would see him step down within 30 days, handing power to a transitional regime headed by his vice president and including some opposition parties. In exchange, Saleh would be granted immunity from prosecution for the crimes committed under his regime and his family would be allowed to keep the vast fortune it piled up over decades.

In the ten days since Saleh fled to Saudi Arabia, an estimated 200 people have been killed in the capital in clashes between security forces and tribal militiamen who have declared their support for the youth protests. It is estimated that over 400 people, mainly unarmed protesters, have died at the hands of Saleh’s security forces since the demonstrations broke out in mid-January.

Tribesmen remain in control of much of the north of Sanaa, and the city is currently crippled by fuel shortages caused by a blockade enforced by tribes opposed to the regime.

Yemen’s second city, Taiz, has also seen fighting between tribal militias and the army. There were reports of fresh clashes in Taiz on Sunday, with government tanks deployed in an attempt to retake control of the city.

In addition to tribal conflicts with the regime, there are intertribal disputes over land and access to water, adding to tensions in the country.

The government, which has dwindling power outside the capital, also faces a regional secessionist movement in the south of the country. The Yemeni army has been involved in heavy fighting in the southern city of Zinjibar, which had reportedly fallen to tribal forces last week.

In an effort to demonize the opposition forces and curry favor with the US, the government in Sanaa has claimed that it was the group Al Qaeda in the Arabian Peninsula that seized Zinjibar, the capital of Abyan Province. On Saturday, the regime claimed that the army had killed 21 Al Qaeda militants in the city, while a senior Yemeni officer and fifteen soldiers had died in the fighting.

However, it is far from clear that Al Qaeda has played a significant role in any of the various antigovernment actions that are unfolding across Yemen. Despite the US launching numerous missile and Predator drone attacks into Yemen, purportedly to kill Islamist militants, Washington has acknowledged that there are only around 250 individuals affiliated with Al Qaeda in the entire country of 24 million people.

With the country on the brink of full-scale civil war, Washington has stepped up its military intervention in Yemen. Though the Obama administration has refused to give details about the bombing campaign, according to a report last week in the New York Times the US is carrying out a major covert campaign against antigovernment fighters. Directed by the Pentagon in conjunction with the CIA, fighter aircraft and drone missiles are being directed by teams of US military and intelligence operatives on the ground inside Yemen.

Since the departure of Saleh for Saudi Arabia, the US has killed suspected midlevel Al Qaeda leader Abu Ali al-Harithi in one of many air strikes focused in the south of the country. US State Department spokesman Mark Toner indicated that, despite its rejection of talks with the opposition, the regime in Sanaa continues to enjoy the support of Washington.

Toner told the New York Times last week that the Yemeni government had to remain focused on dealing with the rebellion and Al Qaeda. “With Saleh’s departure for Saudi Arabia, where he continues to receive medical treatment, this isn’t a time for inaction,” Toner said. “There is a government that remains in place there, and they need to seize the moment and move forward.”

Beyond concerns about a relatively small number of Islamic fighters, US imperialism is working to shore up its authority in this strategically important country. Yemen has long been considered an asset for the major powers, due to its proximity to the Persian Gulf oil fields and strategic sea-lanes.

Southern Yemen was a colony of Britain until 1967, after which the country was divided into Soviet-backed South Yemen and the US-sponsored north, ruled from 1978 by Saleh. The two countries merged in 1990, with Saleh as president of the Republic of Yemen.

Building on these Cold War ties, under the guise of the “war on terror,” Washington has increased its influence on the Yemeni military—the main prop of Saleh’s regime. The US has given some $200 million in military aid to Yemen over the past four years, as well as training Yemeni Special Forces troops.

In addition to concerns that it could lose control of Yemen, Washington is concerned that mass protests and tribal conflicts in the country could spread to neighboring Saudi Arabia, threatening the rule of the US-backed monarchy there.

Not only is Saudi Arabia the world’s biggest oil exporter, it is Washington’s most important ally in the Persian Gulf region. After the fall of US-sponsored dictators Ben Ali in Tunisia, Hosni Mubarak in Egypt, and now Saleh in Yemen, Washington is anxious to prevent the “Arab Spring” from spreading any further.