Even for Yemenis accustomed to the brutal economies of life under a years-long siege, the effect of a blockade of all air, sea and land ports into the country was a surprise.
"Food merchants immediately doubled all their prices. Fuel, in one moment, disappeared from the markets and the price of what remains is insanely high," said Yemeni civil rights activist Baraa Shaiban in a phone interview from London.
"And those who are sick, who need to travel for treatment, they're the worst hit."
The result of the closure by a Saudi Arabian-led coalition could be a famine affecting "millions of victims," said Mark Lowcock, the United Nations undersecretary general for humanitarian affairs, in a briefing at the U.N. Security Council.
"It will not be like the famine that we saw in South Sudan earlier in the year where tens of thousands of people were affected. It will not be like the famine which cost 250,000 people their lives in Somalia in 2011," said Lowcock.
There were reports earlier in the week that Saudi Arabia would allow work to resume at the southern port of Aden, but as of late Thursday, it was unclear whether aid boats had been able to dock, said Jamie McGoldrick, the U.N. humanitarian coordinator for Yemen, in a phone interview.
The coalition's imposition of the blockade on Monday came after the Houthis -- the rebels who seized the reins of power three years ago and whom Saudi Arabia views as a proxy for Iran — launched a ballistic missile targeting the airport of the Saudi capital, Riyadh.
Though the projectile was intercepted, the incident enraged Saudi leaders, who called it an act of war by Iran.
In response, the coalition sealed off the country to "address vulnerabilities" in its inspection procedures, which had already slowed aid deliveries to a crawl in Houthi-controlled ports such as Saleefah and Hodeidah. The latter is the main entry point for roughly 70% of Yemen's food imports, including those reaching the capital, Sana.
The coalition even shut down those entry points under the control of its ally, the internationally recognized government-in-exile of President Abdu Rabu Mansour Hadi, which the coalition has supported with a bombing campaign that human rights organizations say has killed or wounded tens of thousands of civilians. It also imposed a siege beginning in March 2015 that has all but crippled Yemenis' ability to cope and precipitated a wide-scale cholera crisis that has affected some 900,000 people.
The U.S. has provided arms as well as logistical support (including mid-air refueling) to the coalition.
The Red Cross said on Tuesday the latest closure prevented it from delivering a shipment of chlorine tablets, necessary for the prevention of cholera, and fears that it will not be able to deliver 50,000 vials of much-needed insulin.
Humanitarians' access to the country has also been impeded, the U.N. said.
"Saudi is killing Yemenis not only with cluster bombs, but with starvation and disease," said Nasser Arrabyee, a Sana-based journalist, in a phone interview on Thursday. "It's a matter of life and death for us."
Saudi Arabia blamed the Houthis, saying in a letter delivered to the U.N. on Wednesday that their "continued resort to violence, refusal to return to legitimacy and abide by the relevant Security Council resolutions, have resulted in the catastrophic humanitarian situation and is obstructing the political solution to the conflict."
It accused Iran of manufacturing and supplying the missile launched by the Houthis, which it said was "clear evidence of Iran's hostile behavior."
"Iran's continued role in smuggling weapons to the Houthis is a clear sign of its complete disregard for international obligations."
The closures come as part of a larger escalation by Saudi Arabia against what it sees as Iranian interference in the region. Over the past week, it has de-facto deposed Saad Hariri, Lebanon's prime minister, and is holding him against his will, according to Hariri's party.
Nikki Haley, the U.S. ambassador to the U.N., said on Tuesday that her government was "committed to containing Iran's destabilizing actions and will not turn a blind eye to these serious violations of international law by the Iranian regime."
McGoldrick, the U.N. humanitarian coordinator, said that even if aid could reach Aden, it is only one of several ports needed for humanitarian access.
"It's not an alternative, and it doesn't have enough capacity to substitute for" Hodeida and Saleef, said McGoldrick. Aside from food, he added, the lack of fuel, used to pump clean water, has forced people to "take a gamble" on untreated water, potentially exacerbating the cholera challenge.
Shipping aid to Aden would force humanitarians to truck shipments to Sana, almost 200 miles to the northwest, and other Houthi-held areas in the north of the country, a journey of at anywhere from 12 to 18 hours across a chaotic battlefield with dozens of checkpoints run by a patchwork of militias.
It would also allow the coalition to control aid flows in the country — a chilling development for those living in Houthi-controlled areas, said Kristin Beckerle, Yemen researcher for Human Rights Watch.
"Given the coalition's immense power over what goes in and out of Yemen, their ability to affect civilian life is exponential," Beckerle said in a phone interview.
"Forgetting politics, Sana is the largest population center, with people who have nothing to do with the war. It's… willful ignorance of what it means to civilians to close particular ports of entry."
And although she welcomed the opening of Aden's port, she warned that reliance on Aden should not become the permanent arrangement.
"Even before Monday, the U.N. was raising the alarm bells and saying it needs more access… and the coalition did the exact opposite," she said, adding that other closures that hurt civilians, such as the shutting down of the Sana airport in August 2016, had been allowed to become the status quo.
"Aden port will be a positive development from where we were on Monday, but that's not the baseline."
Bulos is a special correspondent.