FORT DRUM, New York (NYTIMES) - President Donald Trump appeared to acknowledge on Monday (Aug 13) something his aides have declined to confirm for months: that his White House had aides sign non-disclosure agreements.

The president made the statement in a post on Twitter about Omarosa Manigault Newman, a former contestant on The Apprentice who became an assistant to the president, and whose new book makes unflattering claims about Trump and his family.

"Wacky Omarosa already has a fully signed Non-Disclosure Agreement!" Trump tweeted, using the type of moniker he often deploys against people who say disparaging things about him.

For months, officials in the West Wing have refused to confirm reports by The New York Times and other news outlets that aides were ordered to sign non-disclosure agreements, which legal experts say are essentially unenforceable for government employees.

Trump, who strives for control over his environment, has for decades demanded that people sign such agreements. Former West Wing officials have said that while they were enacted, members of the White House counsel's office signalled that they could not be enforced, and that they were being executed to reassure Trump.

White House aides did not respond to an e-mail seeking more information about the president's tweet. White House officials have not explained why Manigault Newman was hired, if there were such concerns about her or why she was offered a campaign contract after being fired.

It has been routine for White House officials to be required to sign confidentiality documents acknowledging that they may not publicly disclose classified information to people who do not have the proper security clearance.

But it is highly unusual for White House officials to be asked to sign such agreements for matters beyond classified information.

As stewards of the taxpayers, federal employees typically are not asked to muzzle themselves to protect reputations or insulate others from embarrassment, as is typical in confidentiality agreements that bind private citizens.

They are obliged to respond to disclosure requests from members of Congress and federal agencies, among others. And they enjoy strong whistleblower protections to safeguard their ability to speak out if they witness wrongdoing within the government.

Trump posted throughout the morning about Manigault Newman, dismissing her as a poor employee but saying that he kept her on despite complaints because she has said nice things about him.

In another post, the president retweeted comments made by Michael D. Cohen, his former personal lawyer, who denied an anecdote in Manigault Newman's book, Unhinged, claiming that Trump once chewed up a piece of paper in the presence of both of them to prevent it from being taken by presidential record-keepers. In the past two weeks, Trump's new lawyer, Rudy Giuliani, has painted Cohen as a serial liar as he has appeared to pose a threat to the president.

Manigault Newman has also claimed that she was offered a hush-money contract with the Trump re-election campaign for US$15,000 (S$20,000) a month. A few others who have departed the White House under inauspicious circumstances are receiving that amount.

One White House official insisted that despite the tweets, officials were not bothered by Manigault Newman's news media blitz, which included playing for NBC a tape of Trump calling her. During that call, which she said took place soon after she was fired by John F. Kelly, the White House chief of staff, Trump claimed not to have known that she was dismissed and that he was dismayed.

Kelly fired her in December 2017 in a tense meeting in the Situation Room, the most secure conference room in the White House. Manigault Newman taped that conversation, as well, and released it to NBC, the network on which she appeared during the first season of The Apprentice with Trump.

Officials said they believed Manigault Newman might have many dozens of additional audio recordings, and they were preparing for her to release them slowly, to maximise attention on her book. She is not the only West Wing staff member discovered to have been privately taping the president, three current administration officials said; another, now gone, has been caught during Kelly's tenure.

Privately and publicly, West Wing aides said they think the tapes revealed more about Manigault Newman's disrespect for the institution than it did about her boss.

But veterans of other administrations had a different view.

"He's being hoisted by his own petard," said Ned Price, a former National Security Council official under President Barack Obama. "These are not tactics that belong in government."

David Axelrod, the former chief strategist for Obama, said Trump had essentially set several versions of himself loose and was being stung by it.

"He's created a White House in his own image, and that has led to many, many problems," Axelrod said.

Taping conversations is, in fact, a longtime tactic of Trump's.

For decades, he used it both as an insurance policy and for private titillation as a real estate developer who liked to keep a record, should he ever need it, of phone conversations and meetings, according to former aides.

Staff members warned one another to be careful if they used his phone system at his private club Mar-a-Lago, in Florida, and to be mindful of what they said across his desk at Trump Tower in Manhattan. During the presidential campaign, aides worried that their office on the fifth floor of Trump Tower was bugged.

When Trump arrived in office, he joked to aides about President Richard M. Nixon's infamous Oval Office taping system, saying it must have been nice for him. When Trump contested the claims made by James B. Comey, the former FBI director, that the president had pushed him to end an investigation, Trump tweeted that there might be tapes, a claim he later withdrew.

But in recent weeks, it has been Trump facing a threat from audio recordings, first by his former personal lawyer, Cohen, and now by Manigault Newman, a staff member whom Trump wanted over the objections of his chief of staff at the time, Reince Priebus. Manigault Newman is believed to have tapes of Priebus and other officials.

Cohen taped Trump discussing payments made by The National Enquirer's parent company to a woman claiming she had had an affair with the then-candidate to quash the story. That tape emerged after Cohen's home and office were raided by the FBI.

Price said the episode with Manigault Newman showed that "this is not an administration, it's more a personal fiefdom of Donald Trump".

Tommy Vietor, another former National Security Council official under Obama, said Trump was being outdone by "the people that play that New York tabloid game" that the president had thrived on for decades.

"It seems like it was clear to Donald Trump back in 2013" who Manigault Newman was, he said, "when he would tweet about her character" on the show a decade earlier.