(CNN) — Pressure from the Biden government in the days leading up to the NATO summit culminated months of behind-the-scenes diplomacy to get Turkey to accept Sweden’s membership in the alliance.

Much of this diplomatic effort was to advance the possible sale of F-16 fighter jets to Ankara, a request which, despite claims by senior US officials, had been linked to the issue of Swedish membership in the EU. NATO.

U.S. arms sales to Turkey remain unfinished, and their main challenger is Senate Foreign Relations Committee Chairman Bob Menendez, who told CNN Tuesday afternoon that “for now,” it continues to be against.

The New Jersey Democrat has long opposed selling fighter jets to Ankara, not only because of Turkey’s obstacles to Sweden’s membership, but also because of its human rights concerns. man and regional aggression, including the tension with Greece.

However, there are signs that efforts to change Menéndez’ position and address his concerns have already had some impact.

New information provided by CNN shows how months of constant diplomacy, aided by the close relationship of two former Senate colleagues, resulted in what may be one of the Biden administration’s greatest foreign policy achievements.

All eyes are now on a meeting on Wednesday between Turkish President Recep Tayyip Erdogan and Greek Prime Minister Kyriakos Mitsotakis to see if they can allay US lawmaker concerns and secure approval for the sale of the F- 16.

Ahead of Wednesday’s high-level meeting, the Biden government hopes Erdogan and Mitsotakis will commit to keeping calm in the region and eventually reaching a mutual agreement to respect each other’s airspace, after a year of unprecedented Turkish incursions into Greek airspace, a US official and regional diplomat familiar with the negotiations told CNN. The hope is that the joint statement can address Menendez’s concerns.

Bob Menéndez at a Senate Banking, Housing, and Urban Affairs Committee hearing in Washington in May. (Al Drago/Bloomberg/Getty Images/FILE)

More than a year of promoting Sweden

After Finland and Sweden were invited to join NATO, efforts were launched to secure their membership in the defensive alliance. Turkey put up obstacles for both countries, but ultimately allowed Helsinki to move forward. However, Ankara has maintained its opposition to Sweden’s entry, making demands related to Kurdish terror groups such as the Kurdistan Workers’ Party (PKK) and arms sales.

Behind the scenes, the sale of the F-16s also worked as an implicit request from Ankara, and US diplomats set to work on sweeping compromises both with their counterparts and with lawmakers inside the country. .

These commitments were developed during the many trips to the city of Washington by the American ambassador to Turkey, Jeff Flake.

Flake’s experience as a former U.S. senator from Arizona and his personal relationship with Menendez were key as he tried to explain his former colleague’s position to Turkish officials. He was simultaneously working with another former colleague to figure out how the New Jersey Democrat could achieve a “yes” on the sale of the F-16, a source told CNN.

Flake, along with US Ambassador to Greece George Tsunis, met with lawmakers from the Senate Foreign Relations Committee and the House Foreign Affairs Committee to discuss possible arms sales to the two countries, said a source familiar with the talks.

Flake also visited the Capitol several times in the spring with Erdogan’s top national security adviser, Ibrahim Kalin, to introduce him to members of Congress, the source said. The US ambassador wanted to make sure Kalin understood how important Sweden’s NATO membership was to a wide range of members of Congress, the source said.

Turkish officials also received this message in a bipartisan letter earlier this year, led by Democratic Senator Jeanne Shaheen and Republican Senator Thom Tillis, in which 28 senators said they would not support the sale of F-16s. to Turkey as long as Ankara continues to prevent Sweden from joining NATO, the source said.

The Biden government’s commitments to Hill went beyond visits by senior US diplomats to Greece and Turkey.

US Secretary of State Antony Blinken has reached out to members of Congress, including Menendez, about what it would take to get a “yes” vote to send F-16s to Turkey, a senior US Department official said. ‘State.

“He has had discussions with members of Congress, including Senator Menendez, about this for the past few weeks,” State Department spokesman Matthew Miller said Tuesday.

Meanwhile, government officials have also been holding talks with their foreign counterparts in an attempt to push Turkey forward in Sweden’s NATO bid, a victory won on Monday, on the eve of the summit.

President Recep Tayyip Erdogan with NATO Secretary General Jens Stoltenberg and Swedish Prime Minister Ulf Kristersson during the summit in Vilnius, Lithuania on July 10, 2023. (Photo by TUR Presidency/ Murat Cetinmuhurdar/Anadolu Agency via Getty Images)

Erdogan has agreed to send Sweden’s ratification document to Turkey’s parliament “as soon as possible”, but there is no clear timetable for the country to become the next member of the alliance. Hungary also needs to move forward on ratification, which it should do now that Erdoğan is on board with the plan.

While the White House cleared NATO Secretary General Jens Stoltenberg, Erdoğan and Swedish Prime Minister Ulf Kristersson to take the lead on the important announcement, US national security adviser Jake Sullivan insisted on the key role of President Joe Biden to get to this location.

“When the NATO summit begins, our alliance will not only be bigger and stronger than ever, but it will be more united, more determined and more energetic than at any time in modern history. thanks in large part to President Biden’s personal leadership,” Sullivan told reporters Tuesday morning.

Biden called Erodgan from Air Force One en route to London on Sunday to discuss Stockholm joining NATO and selling the F-16.

“President Biden has always made it clear that he thinks it makes sense for the U.S.-Turkey alliance and bilateral relationship to move forward in this sale,” Sullivan told reporters shortly after his call, adding Tuesday that Biden “intends to move forward with this transfer after consultation with Congress.”

Blinken spoke with Turkey’s foreign minister three times in the five days leading up to the summit, and Sullivan spoke with his Turkish and Swedish counterparts on Monday.

Blinken and Biden have also spoken separately with Mitsotakis in recent weeks as the administration prepared for this week in which they expected to make an intense diplomatic effort.

Biden himself signaled last week that such a deal could materialize, telling CNN’s Fareed Zakaria in an exclusive interview, “What I’m trying to put together, frankly, is a little consortium here, where we strengthen NATO in terms of the military capability of Greece and Turkey, and allow Sweden in. But it’s still in play. It’s not achieved.

Menendez told CNN on Monday that he wanted to see Turkey’s commitment to be “less hostile to a NATO ally” namely Greece, “the commitment to maintain the calm that has existed for a few months” and not that there is “not the use of American weapons against another NATO ally of the United States.”

Tensions between Athens and Ankara have eased in recent months, partly due to the catastrophic earthquake in Turkey, to which Greece has provided assistance. US officials have urged both sides to remain calm, the close source said.