[NATO Secretary General Jens Stoltenberg (R) is welcomed by European Commission President Jean-Claude Juncker prior to a meeting on NATO's mission in Aegean Sea, at the European Commission in Brussels on March 10, 2016]NATO now has five ships taking part in an unprecedented naval mission in the Aegean Sea to tackle people smugglers taking migrants from Turkey to Greece, the alliance's chief Jens Stoltenberg said Thursday.