Turkey's foreign minister announced on Monday that Turkey had sent its fourth ship to the eastern Mediterranean to join the Fatih, Yavuz and the Barbaros survey vessel already anchored off Cyprus.
A US State Department spokesman told the Cyprus News Agency that only the Republic of Cyprus could approve activities such as drilling within its territorial sea.
The spokesman said Washington was particularly concerned about the activities of the Yavuz drilling rig in the exclusive economic zone of Cyprus.
The Spokesman encouraged all parties to act with restraint.
"We urge the Turkish authorities to immediately halt illegal activities and remove Yavuz from the territorial sea of the Republic of Cyprus," he said.
"The development of resources in the Eastern Mediterranean should enhance cooperation and provide the basis for lasting energy security and economic prosperity throughout the region," the spokesman said.
“We continue to support the development of a fair solution to share the benefits of hydrocarbon resources to all parties in Cyprus,” he concluded.