Lindh served 17 years of a 20-year sentence after he was captured in 2001 fighting in Afghanistan.

His early release has sparked fierce criticism, with many believing he still harbours extremist views.

President Trump said of the release: "I don't like it at all", and vowed the government would "watch him closely".

But he said: "From a legal standpoint, there's nothing we're allowed to do."

In an interview with Fox News on Thursday, Mr Pompeo said the move was "deeply troubling and wrong".

Also of note Lindh during his incarceration also expressed support for the Islamic State.