The company usually makes about 400 million masks a year. It is unclear what set off President Trump, but his trade adviser, Peter Navarro, made an oblique reference to 3M at the briefing, mentioning that “we’ve had some issues making sure that all of the production that 3M does around the world,” ends up being sent “to the right places.”

Even as the U.S. grapples with a mask shortage, 3M has continued to sell the critical safety equipment abroad, according to someone with direct knowledge of the matter. It is not illegal for the company to sell its masks to foreign countries. And the U.S. has been slow to respond in a coordinated way or to marshal federal resources, health officials said. That sluggish response has meant that other governments put in orders ahead of the United States.

The investor Mark Cuban, who is advising Project N95, a new nonprofit group that aims to help American hospitals connect with vetted mask suppliers, speculated that the administration may be upset over a perceived lack of transparency from 3M.

“It’s obvious that there’s not enough supply to meet the demand, and it’s obvious that 3M has manufacturing overseas,” Mr. Cuban said. “What’s not obvious is what percentage of their production overseas 3M has been willing to supply.”

Hospitals report some critical medicines are beginning to run low.

Across the country, as hospitals confront a harrowing surge in coronavirus cases, they are also beginning to report shortages of critical medications — especially those desperately needed to ease the disease’s assault on patients’ respiratory systems.

The most commonly reported shortages include drugs that are used to keep patients’ airways open, antibiotics, antivirals and sedatives. They are all part of a standard cocktail of medications that help patients on mechanical ventilators, control secondary lung infections, reduce fevers, manage pain and resuscitate those who go into cardiac arrest.

Demand for these drugs significantly increased in March as the pandemic took hold. Orders for antibiotics like azithromycin and antiviral medicines like ribavirin nearly tripled. Requests for medicines used for sedation and pain management, including fentanyl, midazolam and propofol, increased by 100 percent, 70 percent and 60 percent respectively.