Turkey is seeking to end the North Atlantic Treaty Organization’s naval mission to combat human smuggling in the Aegean Sea even as the mission is receiving a push from other members like the U.S., the U.K. and Germany.

The U.S. announced Wednesday that a decommissioned salvage ship, the USNS Grapple, would join the mission where alliance warships started patrols around Lesbos and Chios islands in the northern Aegean four months ago under an agreement brokered by Germany.

However, Turkey has reportedly blocked efforts to extend the mission to the Kos and Samos islands, which it says are demilitarized zones. It has also asked for the pulling back of the mission as early as next month as it says the operation has achieved its objective, the Wall Street Journal reported, citing NATO officials.

The Turkish representative at the NATO Parliamentary Assembly, Berat Conkar, said refugee crossings from Turkey to Greece have declined significantly since the start of this year, especially after Turkey ramped up efforts in this regard.

“Therefore, we believe that it would be more beneficial and productive for NATO to use its limited military capabilities to carry out its primary duty of protecting the allies,” Conkar told the Journal in a recent interview. However, he declined to comment Wednesday on Turkish calls to end NATO’s mission.

While Turkey has urged the NATO to deploy a fleet in the Black Sea to counter Russian expansion instead, other NATO allies want the Aegean mission to continue as they argue it deters smugglers as well as refugees.

Turkey and Greece have been at loggerheads regarding the continuance of the Aegean mission. In April, Greek Prime Minister Alexis Tsipras said, “Greece will undertake every effort so that NATO’s mission contributes to the solution of the crisis.”

“Unfortunately it's clear that the obstacles ... arise from Turkey's unilateral demands and positions. Demands and positions which unfortunately are also expressed through a rise in activities which violate our airspace,” Tsipras said.

Europe has signed an agreement with Turkey to close off the main route into Europe for refugees trying to cross over to its mainland, hence reducing the stress of migration on European Union states. U.S. Secretary of Defense Ash Carter thanked Turkish Defense Minister Firki Işık for Ankara's efforts to address "irregular migration" to Europe, on the sidelines of the NATO Defense Ministerial meeting in Brussels Tuesday.