The desperate pleas for air cover from Yemeni generals started coming mid-morning on Thursday. An advance by the Iran-backed Houthis toward Yemen's strategic port city of Mocha was in full swing, and backup support from chief ally Saudi Arabia was nowhere in sight.
"The Houthis committed everything they had – waves upon waves of fighters … along with their available ballistic missiles and weapons," a senior Yemeni source attached to their military forces told CNN. The source said he contacted the United States Central Command (CENTCOM) and was assured the US was "watching the situation closely and that Saudi air support was coming."
"But the air support never came," the source said. "And Mocha has now fallen."
Hours later, on Friday, the Houthis captured another key coastal asset, Perim Island, at the mouth of the Red Sea. The island splits the Bab al-Mandeb Strait in two, giving Tehran de facto control over another key shipping route.
The Houthis' rapid advance amounts to an extraordinary 36 hours in a conflict that had been largely on ice for years. But the kindling for renewed fighting had been laid for months amid the conflict between the United States and Iran, as Tehran seeks to use oil prices – and their impact on the global economy – as leverage.
Now, Yemen and the Red Sea have the potential to become a true second front in the Iran war.
Iran's effective control of the Strait of Hormuz plus its tightening grip on the Bab al-Mandeb Strait threatens to push oil prices even higher, weeks before November's midterm elections in the United States.
While the Bab al-Mandeb Strait, the gateway to the Suez Canal shipping route, is less critical to global energy markets than Hormuz, it still carries essential goods worldwide, including millions of barrels of oil every day. The strait has become increasingly important since the start of the Iran war, as Saudi Arabia has re-routed some exports through the waterway to bypass Hormuz.
"(The Houthis) don't need to use advanced weapons to close Bab al-Mandeb. They can just use a cannon on a car," said Amr Al-Bidh, the top official of Yemen's Southern Transitional Council (STC). The STC has fought both the Houthis and Saudi-backed forces in the past, and wants an independent state in the south.
"It's a leverage that they have without using advanced weapons," Al-Bidh told CNN in an interview. "And they will keep it."
Saudi Crown Prince Mohammed bin Salman spoke twice on Thursday with US President Donald Trump and urged him to strike the Houthis, another source familiar with the matter told CNN Friday. Trump declined to intervene, according to that source.
"The United States is focused on protecting our core national security interests—such as ensuring freedom of navigation in the Red Sea—while empowering our regional partners to take the lead in managing and resolving regional security challenges," the White House said in response to CNN's questions about the calls. "We are in continuous dialogue with Saudi Arabia and the Republic of Yemen Government regarding regional stability."
CNN has also reached out to the Saudi Embassy in Washington for comment.
The swift fall of Mocha and the lack of resistance have led to finger-pointing and recriminations among US allies.
"The failure this time is not with the Yemenis," a regional source told CNN on Thursday. "It's a disaster made in (Washington) DC and Riyadh.
The regional source told CNN that it was "a complete failure of political leadership" amid fierce squabbling and delayed decision-making in Riyadh.
"There was not one air strike throughout the day yesterday (by Saudi support forces), although there were minute-by-minute updates," the regional source added. "It's a Saudi-American f**k up of epic proportions."
Not everyone agrees. Mohammed al-Basha, who has served as an adviser to the US government and private sector on risks emerging from the Arabian Peninsula, argues that blame also rests with Yemeni leaders, whose internal divisions jeopardized their defenses.
"This goes back to a deeper problem in the anti-Houthi coalition," the DC-based told CNN. "There is no political cohesion."
"I think everybody was aware of the Houthis' push towards the west coast. The writings on the wall were very clear," he added. "There's no united command and control in Yemen."
Houthi fighters arrived in Mocha on Thursday to find Yemeni battalions that were severely depleted – their rosters were filled with "ghost names" receiving salaries, and the actual strength of the army was only about 20% of what it was on paper, a Western source with knowledge of the operations told CNN.
That was compounded by the fact that the United Arab Emirates – once a member of the Saudi-led coalition in Yemen – withdrew its remaining forces from the country in January, after Saudi Arabia called for them to leave amid a dispute. And Saudi Arabia did not backfill those troop barracks and bases.
"It doesn't make sense. I mean, you have the main backer of the militaries on the ground … who are really doing all of this work for 10 years, and suddenly you ask them to leave, and you don't fill that vacuum," Al-Bidh of Yemen's Southern Transitional Council added. "It's just lack of strategy and poor management."
The senior Yemeni official told CNN on Friday that he had "warned CENTCOM repeatedly over the past few days, including yesterday, that the situation was becoming critical." CNN has reached out to CENTCOM for response.
CENTCOM chief Adm. Brad Cooper was in Saudi Arabia on Thursday for coordination meetings, two sources familiar said. CENTCOM declined to comment, citing operational security reasons.
The Saudi military had been put on high alert three weeks ago, sources told CNN, but they didn't move key air command personnel into place. The Western source with knowledge of the battle said that Saudi Arabia never deployed the necessary service personnel to control and direct combat aircraft in the event of a serious attack.
"The Saudis threw the Yemenis under the bus," the Western source told CNN on Thursday.
CNN has reached out to the Saudi Arabian information ministry for comment on those allegations.
The failure to defend Mocha and Perim is even more confounding in light of the recent news – reported exclusively by CNN – that more than 100 US military advisers were sent to Saudi Arabia providing intelligence and targeting support to the Kingdom in its military campaign, according to five sources familiar with the operations.
The US military personnel are working as part of a newly established joint forces command, which was formed in recent weeks amid signs Iran was ramping up its own efforts to aid Houthi attacks, said one of the sources, a US official. That official estimated the total number of US personnel in Saudia Arabia at roughly 200 troops.
The capture of the Red Sea assets gives the Houthis far greater maneuverability and leverage, as it opens up new locations from which the Iran-backed rebels can launch boats and attacks.
Asked what comes next, al-Basha, the risk analyst, told CNN: "I think the Houthis are going to be moving east. We are seeing today, via satellite and via OSINT (open-source intelligence) photography… that the Houthis are mobilizing."
An adviser to Iran's supreme leader on Friday described the Houthi advance on the west coast of Yemen as a "clear victory," writing in a post on X that "the American people and Washington's allies are paying the price for the economic crisis and Trump's ambitions."
CNN's Sarah El Sirgany, Mostafa Salem, Nadeen Ebrahim, Jennifer Hansler, Zachary Cohen, Katie Bo Lillis and Kylie Atwood contributed to this report.
For more CNN news and newsletters create an account at CNN.com