NATO announced Sunday that it was expanding its mission to help choke off the smuggling of migrants into Europe by deploying warships in Greek and Turkish waters, using more vessels and deepening cooperation with the European Union's Frontex border agency.

NATO Secretary-General Jens Stoltenberg made the remarks in a phone interview with The Associated Press a day before a summit of EU and Turkish leaders in Brussels about the migration crisis.

"We will do reconnaissance, we will do surveillance, we will collect information, and share this information in real time with the Turkish coast guard, the Greek coast guard and with Frontex, helping them with managing the migrant and refugee crisis, and also to cut the lines of the illegal trafficking and smugglers," Stoltenberg said.

The widened mission comes after defense ministers of the 28-nation alliance on Feb. 11 ordered the immediate deployment of three NATO vessels to the Aegean Sea. The waters between Greece and Turkey, two NATO allies, are a key area where smugglers have been bringing tens of thousands of migrants into Europe, sparking what some have called the gravest crisis in the EU's history.

"Now we are going further by actually doing two new things," Stoltenberg told the AP. "We are going into Greek and Turkish territorial waters. We have agreed on arrangements for doing that."

"In addition, we have agreed with Frontex on how to work with them, how to share information so what we will do will be more efficient," the NATO chief said.

NATO officials said the alliance's Allied Maritime Command and Frontex exchanged letters Sunday on specifics of their tactical and operational cooperation.

Now "NATO and Frontex will be able to exchange liaison officers and share information in real time, to enable Frontex, as well as Greece and Turkey, to take action in real time," NATO said in a statement.

Stoltenberg said more NATO ships will also be sent to the Eastern Mediterranean. The German, Canadian and Turkish naval vessels deployed Feb. 11 have been joined by a Greek unit, France has announced it is sending a ship and other allies are expected to follow suit, Stoltenberg said.