The United States has shelved the handover of two leftover frigates to Turkey, as Congress excluded Turkey from a bill seeking permission to transfer vessels to foreign countries, citing Mediterranean tensions, the Hurriyet Daily News reports.

The U.S. approved the “Naval Transfer Act” bill in late December, approving the transfer of six naval frigates to Mexico and Taiwan, but eliminated Turkey over political concerns.

In the 2012 version of the “Naval Transfer Act,” Turkey was to receive two Oliver Hazard Perry class guided missile frigates, the USS Halyburton and the USS Thach, which are being decommissioned by the U.S. Navy.

However, some members of Congress objected to the transfer of naval frigates to Turkey, mainly citing the county’s strained relations with Israel and Greek Cyprus in the Mediterranean.

“I believe we should hold off on sending powerful warships to Turkey and encourage the government in Ankara to take a less belligerent approach to their neighbors,” Congressman Eliot Engel reportedly said during that debate.

Congress members particularly emphasized Turkey’s tension with Greek Cyprus over energy sources off the divided island and its threats against natural gas exploration by American companies in the region.

“Turkey has recently threatened legitimate [Greek] Cypriot and Israeli efforts to cooperation on energy exploration. Ankara has boosted Turkish armed naval presence around the natural gas fields between Israel and Cyprus and declared invalid an agreement between Cyprus and Israel on demarcating their respective energy exploration areas,” another congressman, Brad Sherman, has been quoted as saying.

Turkey is one of around a dozen countries that can manufacture its own warships thanks to its national warship program called Milgem.

Two corvettes designed and built by the local manufacturers, Heybeliada and Büyükada, have been completed in 2008 and 2011. The completed ships have been handed to the Navy, but annulment of the contract with the manufacturer company has slowed down the program.