United States President Donald Trump on Saturday said his former National Security Advisor Michael Flynn’s actions during the transition period were lawful.

Flynn on Friday pleaded guilty to lying to the Federal Bureau of Investigation about his interactions with a Russian official. He said would cooperate with the inquiry into Russia’s alleged attempts to influence the 2016 presidential election in the US.

“I had to fire General Flynn because he lied to the vice president and the FBI,” Trump said on Twitter. “He has pled guilty to those lies.”

The president’s comment, Reuters quoted legal experts as saying, suggested he may have known Flynn lied to the investigative agency before he reportedly urged former FBI Director James Comey to not investigate his former advisor.

If that happened, the president’s tweet “absolutely bolsters an obstruction of justice charge”, said Jimmy Gurule, who teaches law at the Notre Dame University. “It is evidence of the crucial question of whether Trump acted with a corrupt intent.”

Walter Shaub, the former head of the US Office of Government Ethics, also questioned whether the president knew Flynn lied to the FBI when Trump had asked Comey to not investigate Flynn.

Trump’s tweet was drafted by one of the president’s lawyers, according to the Washington Post. Although it does not clarify when the president knew that Flynn had lied to the FBI, it also raises questions about the public relations strategy of Trump’s legal team, the daily said.

It quoted two unnamed people close to the administration as saying that the tweet was “sloppy and unfortunate”.