ΑTHENS – A Russian-made S-300 missile defense system on the island of Crete that Turkey said locked on to its F-16 fighter jets in a NATO exercise – which Greece denied – is not under United States sanctions.

The American State Department said because they were purchased in the 1990s that they don’t fall under the purview of the 2017 Countering America’s Adversaries through Sanctions Act (CAATSA), said Kathimerini.

“Section 231 of the CAATSA Act sanctions only significant transactions that occurred on or after August 2, 2017,” a State Department spokesperson said in response to a question from the Hellas Journal website.

“We continue to encourage all NATO allies to ensure full interoperability within the alliance,” the spokesperson said, although Turkey has bought more advanced and recent Russian S-400 systems that undermine the security of NATO and could be used against Greece in a conflict.

The Crete S-300 system was originally purchased by Cyprus in 1997, triggering a threat response from Turkey, with NATO and the island’s former Colonial ruler, the United Kingdom – which still has bases on the island – pressured for them to be on Crete instead.

Turkey claims that the Crete S-300s locked on to Turkish jets carrying out a reconnaissance mission in international airspace on Aug. 23 as they were accompanying US B-52 bombers.

While Greece said it never happened, Turkish President Recep Tayyip Erdogan said it was a “hostile act,” and has said that Turkish jets that are violating Greek airspace are in Turkish airspace.

It wasn’t reported why there wasn’t evidence either way about the alleged lockons given radar and other technical capabilities and the presence of American bombers on the same run.