The tweet came just after Trump announced that he had asked for former National Security Adviser John Bolton's resignation amid strong disagreements he's had with the administration.
Garry Kasparov, chairman of the Human Rights Foundation, claimed on Twitter that Trump would "fire and drive people away until at last he is surrounded only by people who care only for him and what he can do for them and not about the country at all."
Writer Sarah Kendzior responded by claiming that Ivanka Trump and Kushner would likely stay by Trump's side.
"This is exactly right. It's also why way more attention needs to be paid to Ivanka and Kushner, who are both national security threats," she said in the post retweeted by Messing.
Messing, a vociferous critic of the president, has received attention for recently calling on The Hollywood Reporter to publish the names of people attending a fundraiser for Trump.
She also received criticism for praising a sign that called black Trump voters mentally ill -- something for which she later apologized.
Messing, on Tuesday, also retweeted conservative writer David Frum, who blasted national security officials for refusing to call out the president's alleged incompetence.
"Everybody who works closely with Trump in a national security capacity knows that the president is unfit for his office, but none will tell the public what they say to their intimates," Frum said. "They forgot: they owe their duty to the country to the nation, not to Trump. Speak!"