Joe Biden has invoked emergency powers to speed up the production of baby milk after around half of all stocks disappeared from US stores’ shelves.

The president has “ordered companies to prioritise supplying ingredients for baby milk manufacturers”, The Times reported. He also revealed details of an overseas airlift, nicknamed Operation Fly Formula, pledging that the “military would use commercial aircraft to import supplies while domestic production was being increased”.

The shortage has sent parents across the US scrambling to find supplies of the vital milk. Here is what you need to know about the national crisis.

What is causing the shortages?

Supply chains had been strained during the Covid pandemic. But the problem was exacerbated when one of the biggest suppliers voluntarily recalled its formula after four babies who had consumed its product were hospitalised. Two of the babies died.

Inspectors have since reported “lax safety standards and a history of bacterial contamination in parts of the plant” run by Abbott Nutrition, The Times said. The company shut down its Michigan facility in February, triggering nationwide shortages.

What happened next?

In the months after the plant closed, shortages were reported all over the country and two pharmacy chains rationed how much customers could buy. The issue has led to dangerous shortages, with the Independent reporting that 43% of baby formula was out of stock at retailers nationwide during the week ending May 8, compared to 30% in April.

Leading retailers such as Target, Walmart, CVS and Walgreens have also begun to restrict the amount of formula parents can buy, leaving many empty-handed.

Tins of formula have been listing on eBay “for $120 a pop”, said The Guardian, while the Daily Mail reported that women in Massachusetts were caught on camera “arguing with one another” after one filled her shopping trolley full of baby formula.

The shortage is having a worse effect on the less well-off. Al Jazeera said that “some who have the means and ability are driving long distances in search of the critical nutrients formula” and “paying marked-up prices”.

But the broadcaster said that “struggling families are left without such options” and, in some states, Abbott was the only manufacturer for low-income families receiving benefits.

A mother in Iowa “sprung to action” and donated 45 gallons of breast milk, reported Fox News, while actress Bette Midler tweeted that everyone could just “try breastfeeding”, which is “free and available on demand”.

However, Vox said breastfeeding is “not the answer” to the crisis because some babies cannot be breastfed due to health issues and the practice has many hidden costs, including equipment, classes and extra calories required for the mother.

What is being done?

Biden’s decision to invoke the Defense Production Act means formula producers will have priority when sourcing necessary ingredients.

Abbott Nutrition has also reached an agreement with the Food & Drug Administration (FDA) to restart operations at its factory Michigan. But it “will be weeks until formula supplies are back to normal”, said FDA commissioner Robert Califf, Reuters reported.

In the hope of avoiding a repeat crisis, Democrats also passed a $28m (£22.4m) bill that will boost FDA funding to inspect domestic and international formula producers.