Former US national security adviser John Bolton has reappeared on Twitter, claiming he was denied access to his account after leaving office in September.
On Friday, Bolton wrote on Twitter: "We have now freed the Twitter account, which was previously unfairly banned following my resignation as national security adviser."
"Out of fear for what I might say? To those who speculated that I disappeared. I'm sorry I disappointed you."
"The White House never gave me access to my Twitter account," he said. "Thanks to Twitter for sticking to its community standards and getting it back to me."
Bolton's name was repeatedly echoed during the ongoing investigation against US President Donald Trump. Witnesses said he was aware of Trump's contact with the Ukrainian president and opposed the back channel of pressure on Ukraine.
His lawyers have indicated that he may have additional information for members of Congress.
Trump denied that the White House had closed Bolton's Twitter account in an interview on Fox News.
A senior administration official said the White House did not prevent Bolton from accessing his personal Twitter account, "nor does he have the technical means to do so."
Bolton has spoken publicly since he left the White House and has been regularly appearing on news programs, sparking controversy as to whether he needs calculation to speak.