– President Donald Trump appeared to acknowledge on Monday something his aides have declined to confirm for months: that his White House had aides sign nondisclosure 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 have refused to confirm reports that aides were ordered to sign nondisclosure 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 signaled 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. 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 on Monday dismissed Manigault Newman as a poor employee but said that he kept her on because she has said nice things about him.

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

One White House official insisted that officials were not bothered by Manigault Newman's 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 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 also taped that conversation and released it to NBC.

Officials said they believed that Manigault Newman might have many dozens of additional audio recordings, and they were preparing for her to release them slowly. 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.

Veterans of other administrations had a different view.

"He's created a White House in his own image, and that has led to many, many problems," said David Axelrod, former chief strategist for President Barack Obama.

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 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.