The free messaging app Signal has made headlines after the White House confirmed it was used for a secret group chat between senior US officials.
The editor-in-chief of the Atlantic, Jeffrey Goldberg, was inadvertently added to the group where plans for a strike against the Houthi group in Yemen were discussed.
It has caused a significant backlash, with Democrat Senate leader Chuck Schumer calling it “one of the most stunning” military intelligence leaks in history and calling for an investigation.
But what actually is Signal – and how secure or otherwise were the senior politicians’ communications on it?