In September, the US president said that he had asked Bolton to resign because his services were no longer needed, pointing out that many in his administration disagreed strongly with Bolton's suggestions on US foreign policy.
Bolton greeted his followers Friday and dispelled speculation that he "went into hiding", saying that he would use his account in the future.
|Glad to be back on Twitter after more than two months. For the backstory, stay tuned", Bolton said.
Netizens, however, seemingly have not sharing Bolton's personal delight about his online comeback, hurled a stream of mocking, angry tweets urging the former senior official to testify in Congress - a demand regarding the ongoing impeachment probe against his former employer, US President Donald Trump.
Trump earlier in the day denied that the White House had frozen Bolton's account, insisting that he had a "good relationship" with the former national security adviser.
The impeachment hearings have shown that Bolton previously strongly opposed Trump's decision to have personal lawyer Rudy Giuliani lead foreign policy decisions in Ukraine, as they held security assistance aid while seeking assurances that Kiev would launch investigations into Trump political rival Joe Biden and his son Hunter Biden.
Last month, a former Trump adviser on Russia, Fiona Hill, reportedly told House impeachment investigators in closed-door testimony that Bolton was troubled by a meeting held on 10 July with other US administration officials, including US Ambassador to the EU Gordon Sondland, in which the issue of investigating the Bidens was raised.
House Democrats allege that Trump pressed Ukraine President Volodymyr Zelensky to open a probe into the Bidens by withholding nearly $400 million in US military aid - a charge Republicans deny, pointing to the release of the cash several weeks prior to the Trump's 25 July request, even though Ukraine never launched a Biden investigation.
Trump declassified what the White House claims is the full, unedited transcript of his telephone call with Zelensky. The president denied wrongdoing in his dealings with Ukraine. Trump has described the impeachment inquiry as a political "witch hunt" by Democrats aimed at reversing the outcome of the 2016 US presidential election.
Bolton's attorney, Charles Cooper, said earlier that his client has information about conversations relevant to the Trump impeachment probe.