A second consecutive day of violence in Yemen's capital raised fear of deepening instability in a nation regarded as pivotal to Washington's counter-terrorism efforts in the Middle East.
Assaults by Houthi rebels on Tuesday had sparked speculation that the U.S.-backed government in Sana could fall, prompting an urgent meeting of the United Nations Security Council in New York. But by early Wednesday, President Abdu Rabu Mansour Hadi appeared to be maintaining a tenuous hold on power.
Houthi forces now in effect control the presidential palace and Hadi's residence, according to reports here. But officials said the president was safe and a measure of quiet descended over the capital Tuesday evening.
Officials in Washington were keeping a close watch on the situation, given Yemen's strategic location and its role as an ally of the United States and Saudi Arabia. The Yemeni government has given U.S. forces wide latitude to carry out drone strikes against Al Qaeda in the Arabian Peninsula, a potent Al Qaeda franchise based in the country, and there is concern that a collapse would strengthen the militant group's position.
Al Qaeda, an adversary of the Yemeni government and the Houthi rebels, did not appear to be involved in this week's fighting.
Houthi leaders denied that they were pushing for a coup, describing the attacks as a response to provocations, including shots fired at a Houthi patrol. Military units guarding the presidential palace appeared to have surrendered without a major battle.
The government lost control of the capital in September, when Houthi fighters entered the city largely unopposed and set up checkpoints, eventually expanding their presence to key installations. But the assault on the presidential sites prompted concern that the Houthis might overthrow the government.
In a long televised speech Tuesday evening, rebel leader Abdel-Malek al-Houthi assailed officials in Hadi's government as corrupt and "putting their interest ahead of the Yemeni people."
But the Houthi leader seemed to indicate that negotiations would continue with Hadi's administration about political and constitutional issues as the rebels seek to maximize their power base in a future Yemeni government. He also pointedly praised the national army.
Analysts generally say the Houthi leadership, which represents a minority concentrated in Yemen's north, is more interested in a dominant role in a new government than in running the country directly.
Diplomats and the White House expressed alarm about the quickly deteriorating security situation in Yemen, which has endured political turmoil and sporadic violence since "Arab Spring" protests that erupted in 2011 led to the ouster of President Ali Abdullah Saleh.
As of late Tuesday, U.S. officials said they weren't evacuating the American Embassy in Sana, though an embassy vehicle in the capital was targeted by unknown gunmen late Monday.
The gunmen first fired in the air, then at the vehicle, which was carrying embassy personnel. No one was hit, the embassy said in a statement.
"We strongly condemn the violence and those stoking it in an effort to disrupt Yemen's political transition," the White House said Tuesday in a statement.
President Obama has pointed to Yemen as a major success of his counter-terrorism strategy.
U.N. Secretary General Ban Ki-moon called for "a restoration of the full authority of legitimate government institutions."
Ban also dispatched the U.N. special envoy for Yemen, Jamal Benomar, to Sana.
Hadi, tasked with overseeing a transition to democracy after Saleh's tumultuous departure, has had little success in confronting myriad complex challenges, including widespread poverty and corruption, the Al Qaeda-led insurgency, a southern secessionist movement and the advance of the Houthi rebels, who have emerged as perhaps the nation's most powerful force.
Still, Hadi, elected in a 2012 vote in which he ran unopposed, has the backing of much of the international community and is viewed by Washington as a key regional ally and a bulwark of joint U.S. and Saudi Arabian interests.
Saudi and U.S. officials are wary of the Houthi rebels, who mostly follow a branch of Shiite Islam and are reported to be close to Shiite Iran, though Tehran denies aiding the group. Saudi Arabia — which, like Yemen, is a predominantly Sunni Muslim nation — is engaged in a regional power struggle with Iran and views the reported Houthi-Iranian alliance on its border with considerable unease.
Meanwhile, Yemen-based Al Qaeda militants have been key targets in the U.S. drone war, which has drawn criticism here because of civilian casualties. Yemen not only borders Saudi Arabia, but also abuts key shipping lanes in the Red Sea and Gulf of Aden.
The Houthis are archenemies of Al Qaeda and have accused the government of not going after Al Qaeda more forcefully. But the rebels are also suspicious of the U.S.-Saudi alliance and may not be as open to U.S. counter-terrorism efforts in Yemen, analysts say.
Still unclear is the extent to which Iran has supported the Houthis.
Iran has no interest in creating a power vacuum in Sana that would leave the capital, and the country, more vulnerable to Al Qaeda-style Sunni militants, said Geneive Abdo, a Middle East policy analyst with the Brookings Institution and the Stimson Center.
"If the Iranians are behind this, there won't be a coup," Abdo said. "The Iranians are smarter than that."
Deposing Hadi would "risk a Saudi-led government taking power in Yemen and sending in troops," Abdo said. "The Iranians have a lot to lose if a power vacuum develops, as they know the Houthis can't run the country."
The rebels have been consolidating territorial gains and pushing for political and constitutional reforms that will expand Houthi influence. Critics have accused the well-organized Houthis of mounting a power grab and collaborating with forces still loyal to Saleh, the deposed strongman.
Farea Al-Muslimi, a visiting scholar on Yemen with the Carnegie Middle East Center, who was in Sana and monitoring the clashes Tuesday, said the Houthis appeared to be trying to take over the seats of power "but with zero responsibility" for governing the divided and impoverished country.
"This is definitely the best thing that could happen for AQAP in 10 years," he said in a telephone interview from Sana, referring to the Al Qaeda affiliate by its acronym. "The Houthis will say they are not responsible for what goes on in the south, where AQAP is active. It will be the worst thing that could happen to Yemen."
Houthis account for about a third of Yemen's 26 million people.
In clashes this week, the Houthis are also reported to have seized control of the grounds of a major military brigade and about 280 modern tanks, according to reports here.
On Monday, artillery battles erupted near the presidential palace between Houthi militiamen and government soldiers.
Information Minister Nadia Sakkaf tweeted that the president was "under attack by armed militias seeking the overthrow of the ruling system."
Last week, Houthi forces were accused of kidnapping the president's chief of staff, Ahmed Awad bin Mubarak. The aide reportedly backed a plan to divide the nation into six regions, a move opposed by the Houthis, who see any such division as a dilution of their power.
Government and Houthi representatives reportedly were still negotiating his release.
Special correspondent Al-Alayaa reported from Sana and Times staff writer McDonnell from Beirut. Times staff writers Carol J. Williams in Los Angeles and Paul Richter in Washington contributed to this report.