Several New York Times journalists have been summoned to testify under oath by the US Department of Justice (DOJ) after they reported on security concerns involving the new Air Force One gifted by Qatar.
It marked a dramatic escalation of President Donald Trump's campaign against the media.
The new aircraft, a present from the US ally which has been retrofitted and upgraded at a cost of $400m (£298.5m), entered service last week.
However, Mr Trump used an older Air Force One jet to depart from a NATO summit in Turkey, with the president later citing threats made against him by Iran.
Mr Trump had flown to Ankara in the latest presidential aircraft, a Boeing 747-8. But he left on Wednesday aboard an older Air Force One headed for Mildenhall, a Royal Air Force base in Suffolk, England.
The unexpected swap came after a fragile ceasefire with Iran collapsed, with the US launching airstrikes and Tehran attacking three Gulf states. Iran and Turkey share a border, and there was speculation that the new aircraft lacked certain sophisticated security systems.
And the Times, citing anonymous sources, reported that the switch had come at the urging of the Secret Service, and that the newer plane lacked some of the advanced features of the older aircraft, including anti-missile capabilities.
Mr Trump denied any security concerns, saying on social media that the stop in Mildenhall was so that service members there could take a look at the new jet. During the flight, Mr Trump denied to the reporters accompanying him that security concerns involving Iran were a factor in flying two planes home.
Asked if he was aware of any credible threats against Air Force One by Iran, Mr Trump responded, "I have a threat all the time. I'm No. 1 on their list."
The subpoenas - legal documents ordering someone to appear in court - aim to force the reporters to testify before a federal grand jury in Manhattan, New York, next week, the Times said, adding that federal agents delivered some subpoenas to the reporters' homes.
They were issued after FBI director Kash Patel and other Justice Department officials met at the White House on Friday to discuss the matter, according to a person familiar with the talks who was not authorised to speak about the issue publicly and spoke on the condition of anonymity.
It also said that prior to its first story being published, a senior official at the FBI contacted a reporter and editor to ask that the article be held, referencing national security issues.
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The newspaper said that the FBI official declined to elaborate on the issue, but asked The Times to disclose its sources for the story, which the publication said it refused to do.
"The appearance of federal law enforcement agents on the doorstep of news reporters should shock the conscience of any American who believes in the Constitution and the press freedom it protects," a lawyer for the Times, David McCraw, said in a statement.
The White House did not respond to messages seeking comment about the subpoenas of the Times journalists.
Bruce D Brown, president of the Reporters Committee for Freedom of the Press, said Mr Trump's "war on the press is looking for another victim".
He also said in a statement that the subpoenas "break from longstanding Justice Department practice to protect the public interest and press independence by requiring prosecutors to only seek information from reporters as a last resort when all other avenues have been exhausted".
The Justice Department said that "to be clear, reporters are not the targets, those leaking classified information are".
A statement said: "We value and appreciate the important role that the press plays in this country, but DOJ also plays an important role to make sure that the people entrusted with our nation's secrets do what they're supposed to do with that information, which means not sharing classified information."
While recognising "there may always be natural tension there", the department added "we are not going to ignore the law and stop investigating the people who work in the administration and think it's okay to leak classified information impacting national security".
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