Turkey, which boasts the second-largest army in NATO, announced last week, on Tuesday, it had inked a deal to buy an S-400 (NATO version SA-21 Growler) missile defence system for $2-3 billion from Russia.

Ces 5eThe deal led NATO members to question Turkey’s move and what it means for their alliance with NATO.

The parties did not share the details of the S-400 agreement due to its…