Two months after ascending to the throne, King Salman of Saudi Arabia bet his prestige as a new leader on rallying his Arab allies for a military campaign to save Yemen from an Iranian takeover - all under the direction of his son, the new defense minister and chief of the royal court.
The results a week later showed just how big a risk they took.
Houthis, portrayed as Iranian proxies by the Saudis but few others, havecontinued their advances despite nine nights of Saudi-led airstrikes. On Thursday, Houthi fighters captured a presidential palace in the southern port of Aden, killed a Saudi soldier in a skirmish at the border and wounded five others.
Islamist militants, meanwhile, capitalized on the chaos caused by the airstrikes to free a leader of al-Qaida and hundreds of others from prison and to partly seize control of a crucial city in the south.
Regional militias are battling one another with little thought of the exiled president whom the Saudis had hoped to restore. A week of clashes in Aden have left bodies lying in the streets. The state has collapsed, and aid groups warn of an escalating humanitarian crisis as the military campaign has shut down airports and seaports; worsened shortages of food, water and medicine; and killed scores of unarmed civilians, including internal refugees.
Of concern to Washington, which has provided logistical and intelligence support for the Saudi offensive, the widening civil war is already strengthening the Yemeni branch of al-Qaida, a prime target of its counterterrorism strategy. But analysts say it also risks destabilizing Saudi Arabia, a crucial ally in the region, and increasing the Houthis' reliance on Iran.
"I don't think they have thought through how to solve the problems in Yemen or even how to manage it," said Bernard Haykel, a professor of Near Eastern studies at Princeton University. "I don't know how the Saudis can insulate themselves from Yemen and the violence that will come out of it."
For some who had opposed the Houthis, the bombing campaign seems to be turning their anger against Saudi Arabia instead.
"A real enemy would never do what Saudi Arabia is doing, let alone a neighboring Muslim country," said Mohamed Saleh al-Humidi, an opponent of the Houthis in Sanaa, the capital and a city of 2 million hit by Saudi airstrikes every night for more than a week.
The stakes may be highest for the Saudi king's son, Prince Mohammed bin Salman, whom the king named both defense minister and chief of the royal court. The Saudi government has not disclosed Prince Mohammed's age, but he is believed to be around 30. He was one of the only men in his generation of the royal family to be educated entirely in Saudi Arabia, with no schooling abroad.
The Saudi media have played up Prince Mohammed's role as the architect and overseer of the Yemen campaign, turning it into a pivotal test.
"There is a huge public relations campaign about how wonderful and brilliant the son is, and if the war were to stop now, he would come out looking great, but not if they start taking casualties," Haykel said.
"There is some competition within the royal family," he added, noting that the prince "has amassed an enormous amount of power, and a lot of people are very jealous."
Madawi al-Rasheed, a Saudi professor at the Middle East Center at the London School of Economics, wrote last week in the online magazine al-Monitor that the king and his son were "determined to establish Saudi Arabia as the policing agency of the Arabian Peninsula." "Mohammed's credentials are yet to be established in an external war that is still ambiguous, dangerous and perhaps catastrophic for both Yemen and Riyadh," she wrote.
U.S. officials said they supported the Saudi campaign mainly because of a lack of alternatives.
"If you ask why we're backing this, beyond the fact that the Saudis are allies and have been allies for a long time, the answer you're going to get from most people - if they were being honest - is that we weren't going to be able to stop it," said a U.S. defense official, speaking on the condition of anonymity because the official was discussing internal government deliberations.
"If the Saudis were willing to step in the thinking was that they should be encouraged," the official said. "We were not going to send our military, that's for certain."
Robert Jordan, a former U.S. ambassador to Saudi Arabia, said, "The Saudis run a risk of alienating much of the Yemeni population because of these airstrikes."
"This war could last for a long time, yes," said Mustafa Alani, a scholar at the Gulf Research Center who is close to the kingdom's rulers.
"The Saudis consider the risk of not doing anything far greater than the risk of taking action," he said, adding, "It is not a pleasant experience, but it would be worse if you did nothing."
But he also acknowledged that the end game remained difficult to predict. Saudi Arabia has said it is seeking to preserve President Abed Rabbo Mansour Hadi as Yemen's legitimate leader, but Alani acknowledged there appeared to be little chance that Hadi, believed to be in Saudi Arabia, could return to rule Yemen alone. "He does not have charisma, and he does not have a power base," Alani said.
The Saudi reasoning behind the campaign rests on what most analysts outside the kingdom say are flawed assumptions about the nature of the Houthi movement.
An indigenous group based in North Yemen, the Houthis practice a variant of Shiite Islam and have received financial support from Shiite-led Iran. But many Yemenis and Western diplomats say the Houthis are independent of Tehran. They have fought six conflicts against the Yemeni government since 2004, and scholars say they began receiving Iranian support only in the past few years, since about 2010.
The Houthis owe their recent military successes to considerable battlefield experience and to their alliance with units of the military and security forces still loyal to Ali Abdullah Saleh, Yemen's former autocratic leader who was forced from power by the uprisings during Arab Spring but remains a power broker in the country.
The Saudi intervention may bolster the Houthis by shielding them from criticism that they have become too domineering in Yemen, said April Longley Alley, a Yemen researcher at the International Crisis Group.
"There was domestic resistance forming that was going to be part of the solution," said Alley, adding that no one faction - including the Houthis - would have been able to govern Yemen on its own.
But the entrance of the Saudis layered additional regional dynamics, sectarian rhetoric and domestic Saudi considerations onto the conflict, "prolonging and complicating the struggle inside the country," she said.
As a result of the Saudi offensive, the Houthis had become more determined to advance militarily while solidifying their alliance with Saleh, Alley said. The Saudi role has also further divided northern and southern Yemen, as public opinion has hardened against Saudi intervention in the north while the south has favored more airstrikes.
Fighting in Aden over the past few weeks has provided a glimpse of a pitiless war ahead. The city has been ravaged by urban fighting between the Houthis and local militias, leaving dozens of civilians dead. Residents were bracing for intensifying strikes by the Saudis and their allies, after the Houthis seized control of more territory Thursday.
Seizing on the chaos, al-Qaida on Thursday mounted its first large-scale operation since the Saudi airstrikes got underway.
In a coordinated attack on al-Mukalla, the capital of oil-rich Hadhramaut province, the militants seized government buildings, including the central bank, and stormed the central prison, freeing Khalid Batarfi, a senior regional al-Qaida leader and other operatives of the group, according to witnesses and local news reports.
Al-Qaida and other Sunni extremists stood to "benefit from prolonged instability and conflict," Alley said. "What we see in al-Mukalla is a harbinger of more to come."