NATO has agreed to patrol the Aegean Sea to deter people smugglers taking migrants to Europe.
The alliance's secretary-general, Jens Stoltenberg, made the announcement on February 11 after a request from Germany, Greece, and Turkey at a defense ministers meeting in Brussels.
Stoltenberg said NATO ships were being deployed to the waters between Turkey and Greece "without delay."
He said the mission would not be about "stopping or pushing back refugee boats," but would contribute "critical information and surveillance to help counter human trafficking."
According to the UN refugee agency, nearly 75,000 migrants have already arrived in Greece by sea this year.
The International Organization for Migration says more than 400 people have died while attempting to cross the Mediterranean Sea.
It would be the first time the military alliance has gotten involved in Europe's migrant crisis.
The sea and land borders between Greece and Turkey have been the main access point to the European Union for 80 percent of migrants, including refugees fleeing the Syrian civil war.
Under the proposed surveillance mission, information gathered by NATO would be passed on to Turkish authorities to go after people smugglers, and Turkey would take back refugees who are picked up by NATO.
NATO already has ships in the eastern Mediterranean as part of efforts to shore up Turkey's defenses against missiles from Syria.
Earlier, U.S. Defense Secretary Ash Carter said plans for the NATO deployment will be drawn up by the alliance's military authorities for review and possible implementation.
Carter also said he expected a meeting of more than 20 countries contributing to the war against the Islamic State (IS) group in Syria and Iraq to endorse a U.S. plan for accelerating the campaign.
He said he would lay out details of the plan at the Brussels gathering later on February 11.
The Pentagon chief said he would ask coalition members to find ways to increase their contributions, either militarily, financially or in other ways.
Based on reporting by AFP, Reuters, AP, dpa