NATO will back a German, Greek and Turkish mission to monitor and combat people smuggling across the Aegean Sea between Turkey and Greece.

Defense Secretary Ash Carter made the announcement Thursday after a meeting of defense ministers at alliance headquarters in Brussels, saying: "NATO and all the parties at the table this morning indicated a willingness for NATO to support and be a part of that operation.

"All three of those countries emphasised the need for NATO to act quickly, with which the United States strongly agrees, because this are people's lives and destinies at stake here."

Speaking after the meeting, NATO Secretary General Jens Stoltenberg said the bloc's Maritime Group was being ordered to the area immediately with the warships - now under German command - to monitor the area as part of the mission.

German government sources say that Germany, Greece and Turkey want NATO to start monitoring the Aegean Sea to give a "clear view" of how people smugglers are working on the Turkish coast.

Turkey is the main jumping-off point for the more than 1 million refugees who arrived in Europe in 2015 - Europe's worst migrant crisis since World War II. Once they reach Greece, many of those people travelled through to Germany, France and Scandinavia.

But to get to Greece, they have to cross the Aegean Sea, something more than 70,000 people did in January alone - more than 400 of them dying in the attempt since then, according to the International Organisation for Migration.

Many are from countries such as Syria, Iraq, Afghanistan and those in northern Africa.

There are fears that, with the war in Syria having killed more than 260,000, displacing half the population since March 2011 and showing little prospect of a resolution, many thousands more people could attempt the dangerous crossing.

"There is now a criminal syndicate which is exploiting these poor people," Carter said. "Targeting that is the greatest way an effect could be had."

NATO's military chiefs have been asked to compile a mission plan and the bloc's Military Committee will review this before passing it on to the North Atlantic Council - NATO's main decision-making body.

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