After Donald Trump unleashed a Twitter tirade against Barack Obama for baseless allegations of “wiretapping,” many wondered how the former president would respond to the egregious claims.

According to aides of the former president, Barack Obama was “furious,” irked and exasperated upon learning that his successor published an uncorroborated allegation that he wiretapped Trump Tower, reported CNN.

Trump labeled Obama a “bad or sick guy” in his tweets accusing him of using his executive power to wiretap Trump Tower during the final stretch of the campaign. According to sources close to Obama, he was “livid” that such a remark was made without any evidence to back it up, reported the Wall Street Journal.

After Trump tweeted the unsubstantiated claim, a representative of former President Barack Obama released a statement citing that a wiretap on an individual would go against the administration’s cardinal rule.

"A cardinal rule of the Obama administration was that no White House official ever interfered with any independent investigation led by the Department of Justice," said Obama's spokesman, Kevin Lewis. "As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any US citizen. Any suggestion otherwise is simply false."