Defend ‘every inch’ of NATO territory? New strategy is a work in progress.

They left France in the early hours, flying north and east over sleeping cities until they were less than 100 miles from the Russian border. Then, they jumped.

The French paratroopers who floated into the fields of Estonia in May were part of a stepped-up rehearsal of what it would take to reinforce a battle group if the country — and NATO — were attacked.

Before Russia launched its invasion of Ukraine last year, the multinational troops stationed in the Baltics and Poland were intended as a “tripwire” — a presence just...