Grenell was Trump's ambassador to Germany for a couple of years before he was made Acting Director of National Intelligence (because he'd already been confirmed by the Senate for the ambassador gig).
So technically he can be referred to as Ambassador Grenell, though it's more usual to address him by the more recent and higher-ranking title of Former Acting DNI.
Grenell was Trump's ambassador to Germany for a couple of years before he was made Acting Director of National Intelligence (because he'd already been confirmed by the Senate for the ambassador gig).
So technically he can be referred to as Ambassador Grenell, though it's more usual to address him by the more recent and higher-ranking title of Former Acting DNI.