Plans for an attack against an enemy target are classified in the United States. But the private views of high-ranking officials about allies, communicated within government, must also count as intelligence to be protected.
The recent communication of this category of information over the Signal messaging app has been dismissed by the US president, Donald Trump as a mere “glitch”. It is definitely that. But it also raises the prospect that in his first two months of office, key parts of the administration might have inadvertently been leaving sensitive information vulnerable to enemy interception. That would be one of the most serious intelligence breaches in modern history.

