Donald Trump threatened to jail a journalist – or journalists – who reported that a second US airman was missing after being shot down by Iran on Friday in a bid to identify their source.

The badly injured airman hid in a mountain crevice to avoid capture before being rescued by a US recovery team that took on heavy fire. The US president announced on Sunday that the service member had been recovered.

During a press conference at the White House on Monday afternoon, Trump told reporters that his government is aggressively pursuing the “leaker” who revealed information about the missing airman to the media. He claimed that the news report put Iran on notice and put the airman in danger.

“They basically said that ‘we have one and there’s somebody missing.’ Well, they didn’t know there was somebody missing until this leaker gave the information,” Trump said. “So whoever it was, we think we’ll be able to find it out because we’re going to go to the media company that released it, and we’re going to say, ‘national security, give it up or go to jail.’

“And we know who – and you know who – we’re talking about. Because some things you can’t do, because when they did that all of a sudden the entire country of Iran knew that there was a pilot that was somewhere on their land that was fighting for his life.”

Trump did not name the outlet, or the reporter, he was threatening.

During his second administration, Trump has ratcheted up his efforts to target media companies that have published reporting he dislikes, regularly threatening lawsuits and restricting access. In January, a Washington Post reporter’s home was raided by the FBI. The reporter, Hannah Natanson, had aggressively covered Trump’s oversight of federal agencies, generating more than 1,000 anonymous government sources that contributed to her reporting. The case is still playing out in a Virginia court.

The White House did not immediately respond to a request for specifics about the media company Trump was referring to.

Seth Stern, chief of advocacy at the Freedom of the Press Foundation, said: “Journalists don’t work for the government and their right to publish government leaks is protected by the First Amendment which, despite Trump’s efforts, remains the law of the land, and does not disappear whenever the words ‘national security’ are uttered. To the extent that the government is allowed to withhold information, it’s up to the government to keep its secrets, not journalists.”