What did Donald Trump do today?

He pissed off the British government during their response to a terrorist attack--again.

A bomb went off on a London train at 8:20 A.M. local time. A few hours later, Trump enthusiastically folded it into his morning tweetstorm, saying that the perpetrators (still unknown) had already been "in the sights of Scotland Yard" which had not been "proactive" enough. (He also called for cutting off terrorists' internet access, which would only be possible if he already knew where they were.)

This prompted immediate rebukes from all levels of the British government, from the Metropolitan Police to Prime Minister Theresa May herself. London's mayor, Sadiq Khan--whom Trump personally attacked during the last terrorist attack on London--refused to engage at all.

It's not clear whether Trump was merely making up the detail about the bombers being known to British law enforcement, or if he was simply broadcasting an ally's classified information. There's ample precedent for both possibilities.

Why does this matter?

• It's bad if a president repeatedly responds to attacks on allies with criticism rather than support.

• It's bad if a president is making up or imagining details of important events.

• It's bad if a president is releasing classified information entrusted to the US by its allies.

• Presidents probably ought to understand the cyber a little better than this.