Greece said it would be extending a wall along its border with Turkey to prevent potential mass crossings by migrants into its territory.
The move comes months after a spike in border tensions after Turkey said it would not be stopping refugees from crossing into Europe.
Relations between the NATO allies have nosedived this year. The two countries have been bickering over a range of issues, including refugees, oil exploration, and the Hagia Sophia monument.
Since the beginning of the Syrian war in 2011, vast numbers of displaced Syrians have sought refuge in Turkey. Turkey hosts some 37 lakh refugees from Syria, and is feeling the socio-economic and political strain of their presence in the country.
In 2016, Turkey agreed to prevent migrants from crossing into the EU, and the bloc in return promised funds to help the former manage the refugees on its soil.
Critics blamed Turkey for using the migrant issue as a means to bring its western allies on board with its military campaign in Syria’s Idlib province, where hostilities had escalated in preceding weeks.
For centuries, Turkey and Greece have shared a chequered history. Greece won independence from modern Turkey’s precursor, the Ottoman Empire, in 1830.
The two nations continue to oppose each other on the decades-old Cyprus conflict, and on two occasions have almost gone to war over exploration rights in the Aegean Sea.