US and British intelligence agencies are able to gain access to personal data from smartphone apps including Angry Birds and social media sites such as Facebook and YouTube, according to documents taken by ex-US spy contractor Edward Snowden.
British intelligence agency GCHQ "would not confirm of deny the existence of the Squeaky Dolphin" monitoring programme, according to NBC News.
A spokesperson for the agency said GCHQ's work was "carried out in accordance with a strict legal and policy framework”.
This "ensure[s] that our activities are authorised, necessary and proportionate, and that there is rigorous oversight, including from the Secretary of State, the Interception and Intelligence Services Commissioners and the Parliamentary Intelligence and Security Committee", the spokesperson added.
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.