Donald Trump will face any number of global challenges when he enters the White House in January, ranging from the ongoing civil war in Syria to battling so-called Islamic State.

Former US Defence Secretary and CIA chief Leon Panetta confronted similar crises during his days in office.

He recently co-chaired a commission that urged the use of a multi-faceted approach to counter violent extremists.

Mr Panetta tells the BBC's Katty Kay that the president-elect will have to work with America's friends and allies if he hopes to succeed in tackling these crises.