NATO Secretary-General Jens Stoltenberg says Russian President Vladimir Putin would be crossing a “very important line” if he were to deploy nuclear weapons in Ukraine. His comments came after a meeting of NATO’s Nuclear Planning Group in Brussels.Asked what the military alliance would do should Moscow launch a nuclear attack, Stoltenberg said, “We will not go into exactly how we will respond, but of course this will fundamentally change the nature of the conflict. It will mean that a very important line has been crossed.””Even any use of a smaller nuclear weapon will be a very serious thing … and of course that would have consequences,” he added.He stressed, however, that the circumstances in which NATO might have to use nuclear weapons are “extremely remote.”The meeting in Brussels came ahead of a planned NATO nuclear exercise, dubbed “Steadfast Noon,” next week. Russia is also expected to hold nuclear drills of its own in the near future.