Greece will make an official request to the United States for the purchase of 20 F-35 fighter jets, defense sources said on Thursday.

The jets, which are made by Lockheed Martin, will bolster the Greek defense forces considerably, in light of an escalation of tension with neighboring Turkey over the last few years. 

According to Greek daily Kathimerini, a source is believed to have said “The relevant document has been signed,” with deliveries of the jets to begin as early as 2027.

“According to state TV ERT the Letter of Request has been signed and is expected to be submitted to the US Embassy in Athens this week. This is the first step in a multi-stage process,” the Kathimerini report stated.

Greece and Turkey, both members of NATO, have been at odds for decades over a number of issues, most notably the extent of their continental shelves and their maritime boundaries to energy resources and ethnically-split Cyprus.