Is Donald Trump is a danger to national security?

An open letter signed by 50 Republican national security experts has warned that nominee Donald Trump "would be the most reckless president" in US history.

General Michael Hayden, director of the CIA between 2006 and 2009 and one of the signatories, told World at One's Martha Kearney that the presidential nominee would be "very dangerous indeed" for national security.

Dr Michael Scheuer, a CIA officer for 22 years who has endorsed Donald Trump, said the group behind the letter "deserved to be ignored".