The two leaders spoke within hours of the prime minister being diagnosed with coronavirus – and amid fierce criticism of his failure to take up the EU’s offer to jointly obtain the life-saving equipment.
Revealing the contents of the call, Mr Trump said: “I say ‘how are you feeling’ and the first thing Boris said to me is ‘we need ventilators'”
The US was willing to “help the UK”, despite the gathering crisis in the country which is now identified as the hotspot of the pandemic, the president said.
The call came after Brussels ridiculed the UK’s claim that a communications mix-up explained its decision not to join an emergency EU scheme to procure ventilators and other desperately-needed equipment.
The NHS has only 8,000 ventilators – when 30,000 are likely to be needed – and only a further 8,000 are expected to be ready before the expected peak of the epidemic, in mid-April.
Mr Trump told a press conference: “We can help the UK – Boris Johnson specifically.
“As you know Boris, he’s tested, unfortunately he’s tested positive and that’s a terrible thing. But he’s gonna be great I’m sure he’s gonna be totally great.
“But they want ventilators, Italy wants ventilators, Spain wants ventilators, Germany wants ventilators.”
The prime minister has spoken with the bosses of a dozen companies he is urging to lead the effort to reach the target of 30,000 ventilators.
However, James Dyson was not among them after Downing Street shot down claims that he had secured a contract to supply 10,000 – because regulatory approval has not been secured.
Instead companies including Airbus, McLaren, Ford, Rolls-Royce, Babcock, Siemens and Renault are involved.
No 10 initially said it did not join efforts because “we are no longer members of the EU”, before backtracking after criticism.
It then claimed the UK had missed the procurement deadline due to a “communication problem”, which meant the country was not invited to apply in time.
But a European Commission spokesperson said: “The member states' needs for personal protective equipment have been discussed several times in the meetings of the health security committee where the UK participated.
“At these meetings, the commission stressed its readiness to further support countries with the procurement of medical countermeasures if needed, so member states and the UK had the opportunity to signal their interest to participate in any joint procurements.”