Biden applauds Turkey's agreement to back Sweden's NATO entry on summit eve

Turkey is dropping its opposition to Sweden's bid to join NATO, a big development on the eve of the alliance's 74th annual summit in Vilnius, Lithuania.

The announcement was applauded by President Joe Biden and comes a day after he spoke with Turkey's President Recep Tayyip Erdogan about U.S. F-16s for Ankara, although any direct connection was unclear.

NATO Secretary-General Jens Stoltenberg announced Monday an agreement was reached between him, Erdogan and Swedish Prime Minister Ulf Kristersson.

Stoltenberg called it a "historic step" that will strengthen NATO allies.

Biden, who was vocal in supporting Sweden's membership, was quick to celebrate the breakthrough.

"I welcome the statement issued by Türkiye, Sweden and the NATO Secretary General this evening, including the commitment by President Erdogan to transmit the Accession Protocol for Sweden to Türkiye's Grand National Assembly for swift ratification," Biden said in a statement.

"I stand ready to work with President Erdogan and Türkiye on enhancing defense and deterrence in the Euro-Atlantic area," he continued. "I look forward to welcoming Prime Minister Kristersson and Sweden as our 32nd NATO Ally. And I thank Secretary General Stoltenberg for his steadfast leadership."

According to a press statement from NATO, Erdogan agreed to quickly send Sweden's accession protocol to Parliament in exchange for new commitments on terrorism and economic cooperation, including the establishment of a special coordinator for counter-terrorism within NATO.

The Nordic nation's bid also faced opposition from Hungary. Unanimous approval from all member nations is needed in order to join the organization.

Stoltenberg said Monday Hungary has made it clear it will not to be the last to ratify Sweden's application, and believes "that the problem will be solved."

Biden pushed for Sweden to be part of the alliance in an Oval Office meeting with Kristersson last week.

"The United States fully, fully, fully supports Sweden's membership in NATO," Biden told the prime minister. "And the bottom line is simple: Sweden is going to make our alliance stronger and has the same value set that we have in NATO. And I'm really anxiously looking forward for your membership."

The president also conveyed his desire for Sweden's bid to be approved in a call with Erdogan on Sunday, the White House said.

The two leaders also discussed the delivery of American F-16 fighter jets to Turkey during the call, which lasted 45 minutes to an hour, White House national security adviser Jake Sullivan told reporters.

Sullivan didn't provide a direct answer when asked if Biden's willingness to provide the equipment was a quid pro quo in exchange for Turkey allowing Sweden to join NATO.

"President Biden has been clear, consistently, that he believes that for the alliance and for the U.S.-Türkiye bilateral relationship moving forward with the sale makes sense. It's in our interest," Sullivan said. "He also believes that Sweden becoming a member of NATO is very much in our interests. And we should do both of these things. And doing both of these things would give real impetus and momentum to NATO and to the bilateral relationship between the US and Türkiye."

Biden arrived in Lithuania on Monday after a stop in London, where he met with U.K. Prime Minister Rishi Sunak and King Charles III. He and Erdogan are slated to meet on Tuesday morning in Vilnius.

The NATO summit is expected to center on continued aid for Ukraine as its launched its counteroffensive against Russian invaders.

-ABC's Fritz Farrow and Molly Nagle contributed to this report.