The U.S. House of Representatives on Thursday approved legislation that would create a new hurdle for President Joe Biden’s plan to sell F-16 fighter jets to Turkey.

The legislation comes just weeks after Washington’s strongest public backing yet for Turkey’s request to renew and modernize its F-16 fleet since it was lodged by Ankara last October.

The House approved the measure, offered by Democratic Representatives Frank Pallone and Chris Pappas, as an amendment to the annual National Defense Authorization Act (NDAA), by 244 to 179.

It is the latest effort by members of Congress, known for its anti-Ankara stance that has repeatedly damaged bilateral relations, to exert control over the sale of the Lockheed Martin aircraft to NATO ally Turkey.

The amendment would bar the United States from selling or transferring the jets to Turkey unless the administration certifies that doing so is essential to U.S. national security and included a description of concrete steps taken to ensure they are not used for "unauthorized overflights" of Greece.

Turkey and Greece have been at odds over issues ranging from overflights and the status of Aegean islands to maritime boundaries, hydrocarbon resources in the Mediterranean and the ethnically split island of Cyprus.

Tensions flared recently over airspace and the status of demilitarized islands in the Aegean.

President Recep Tayyip Erdoğan has said Greek Prime Minister Kyriakos Mitsotakis "no longer exists for him" after the Greek premier lobbied for the U.S. not to sell Turkey F-16 jets during a speech at the U.S. Congress in May.

Erdoğan earlier this month said he refuses to meet with Mitsotakis until the Greek leader "pulls himself together."

Turkey is demanding that Greece demilitarize its eastern islands, citing the 20th-century treaties that ceded sovereignty of the islands to Greece.

There was no immediate response from Ankara or the White House on the limitation.

Biden last month openly threw his support behind the potential sale and modernization of Turkey’s F-16 fleet, saying that the U.S. should go ahead with the delayed sale of Lockheed Martin jets to Turkey.

He said he was confident the congressional approval needed for the sale can be obtained, in remarks that came after Ankara lifted a veto of NATO membership for Finland and Sweden.

"It’s not in our interests not to sell them," Biden said on the sidelines of a NATO summit in Madrid.

"We should sell the F-16 to Turkey. I said that in December, and my position hasn’t changed since then ... We need congressional approval to get there, and I think we’ll get there."

Still, the hurdle presented by the U.S. House of Representatives may not be a difficult one to overcome.

"What we are saying here is that we want some detailed analysis of what is going on here," Democratic Representative Pallone, a co-sponsor of the provision, said during debate on the defense bill, Bloomberg News reported.

"The bottom line is they have not put forward any explanation of how this is in the national interest of the United States."

The process to finalize the defense bill, known as NDAA, is lengthy, and the Senate will also have to back similar language before it can be sent to Biden's desk to be signed into law. Revisions to the bill in its current form are all but certain. The president can veto such legislation.

Senator Bob Menendez, chairperson of the Senate Foreign Relations Committee, who reviews major international weapons deals, has said previously he opposed the sale.

The decades-old partnership between the NATO allies has gone through unprecedented tumult in the past five years over disagreements on many issues, including Syria and Ankara’s closer ties with Moscow.

Turkey made a request to buy 40 Lockheed Martin-made F-16 fighters and nearly 80 modernization kits for its existing warplanes, in what is estimated to be a $6 billion deal.

The sale of U.S. weapons to NATO ally Turkey became contentious after Ankara acquired Russian-made S-400 defense missile systems, triggering U.S. sanctions as well as Turkey’s removal from the F-35 fighter jet program.

The Biden administration has on several occasions signaled its openness to the sale, including Secretary of State Antony Blinken, who has said foreign military sales to key U.S. partners like Turkey should be expedited and bureaucratic hurdles removed.

In March, the State Department wrote a letter to some members of Congress who had opposed the sale, saying "appropriate" U.S. defense trade ties with Turkey would serve U.S. interests.