WASHINGTON - President Joe Biden is welcoming Denmark and Britain’s prime ministers this week to Washington for talks that will focus heavily on what lays ahead in the war in Ukraine - including the recently-launched effort to train, and eventually equip, Ukraine with American-made F-16s fighter jets

Britain and Denmark are playing a pivotal role in the nascent joint international plan that Biden recently endorsed after months of resisting calls from Ukrainian President Volodymyr Zelenskyy for U.S. aircraft

Biden’s separate meetings with the leaders of two key NATO allies - he’ll huddle with Denmark’s Mette Frederiksen on Monday and the UK’s Rishi Sunak on Thursday - come at a crucial period in the 15-month war as Ukraine readies to launch a counteroffensive. It’s also a moment when the U.S. and Europe are looking to demonstrate to Moscow that the Western-alliance remains strong and focused on cementing a longer-term commitment to Ukraine with no end to the conflict in sight.

“One of the things we’ll be looking for their perspectives on and the President will be interested in sharing his perspectives on is the long term security needs of Ukraine,” White House National Security Council spokesman John Kirby said. “And that’s really where the F-16s kind of come into this discussion.”

Denmark has purchased dozens of American-made F-16s since the 1970s and has indicated it is open to providing Ukraine with some. Britain strongly advocated for a coalition to supply Ukraine with fighter planes, and says it will support Ukraine getting the F-16s it wants. But the U.K. does not have any F-16s, and has ruled out sending Royal Air Force Typhoon jets.

Instead, Britain says it will give Ukrainian pilots basic training on Western-standard jets starting in early summer to prepare them to fly F-16s. The Ukrainian pilots will then go on to other countries for the next stages of training.

The F-16 agreement is among several recent high-profile efforts by the U.S. and Europe focused on bolstering Western resolve as the war grinds on. Russia’s Defense Ministry announced early Monday its forces had thwarted a large Ukrainian attack in the eastern province of Donetsk. It wasn’t clear if this was the start of a Ukrainian counteroffensive.

Last week, Frederiksen and Sunak were among 45 European leaders who traveled to Moldova for the first summit of the European Political Community where they underscored support for Eastern Europe’s ambitions to draw closer to the West and keep Moscow at bay.

Biden is also expected to discuss with Frederiksen and Rishi preparations for next month’s NATO summit in Lithuania that comes amid growing pressure on the alliance from Zelenskyy on NATO to offer Ukraine concrete security guarantees and a defined path for Kyiv to eventually win membership into the group.

The 31-member alliance is also looking at boosting Ukraine’s nonmember status in NATO and preparing a framework for security commitments that it can offer once the war with Russia is over.

Max Bergmann, a former senior State Department official during the Obama administration, said Biden and his European counterparts’ task is to stay on the same page for what comes after Ukraine’s much-anticipated counteroffensive.

“Throughout this conflict, we have not only underestimated the Ukrainians but we have also underestimated the Europeans,” said Bergmann, who is now director of the Europe, Russia, and Eurasia Program at the Center for Strategic and International Studies in Washington. “They’re not wavering but they will also need to keep finding new funds to plow into military equipment to support the Ukrainians. There’s a question on both sides of the Atlantic: How much will it actually take to sustain Ukraine?”

Biden is also expected to check in with Frederiksen and Rishi on his effort to press fellow NATO member Turkey to back off blocking Sweden from joining the military alliance.

Sweden and Finland, both historically unaligned militarily, jointly sought NATO membership after being rattled by Russia’s invasion of Ukraine. Turkey initially blocked both countries from joining the alliance before agreeing to membership for Finland while continuing to object to Sweden.

Turkish President Recep Tayyip Erdogan has objected to Sweden’s perceived support of the banned Kurdistan Workers Party, or PKK, the leftist extremist group DHKP-C, and followers of the U.S.-based Muslim cleric Fethullah Gulen, who Ankara claims was behind a failed military coup attempt in 2016.

Erdogan won reelection last week to a third term despite his government’s struggle to deal with runaway inflation and the aftermath of an earthquake that leveled entire cities in the country. Now that his reelection battle is behind him, White House officials are increasingly optimistic that the Turkish leader will withdraw his opposition to Sweden’s membership, according to a U.S. official familiar with internal deliberations. The official was not authorized to comment publicly and spoke on the condition of anonymity.

Biden said he raised Sweden’s NATO application and Turkey’s desire to buy 40 new F-16s from the U.S. - a move some in Congress oppose until Turkey approves NATO membership for Sweden - during a phone call last week with Erdogan.

“He still wants to work on something on the F-16s. I told him we wanted a deal with Sweden, so let’s get that done,” Biden told reporters shortly after the call.

Days later, at his commencement address at the U.S. Air Force Academy in Colorado, Biden spoke with certainty about Sweden’s NATO membership hopes. “It will happen. I promise you,” Biden said.

NATO Secretary-General Jens Stoltenberg and U.S. Secretary of State Antony Blinken both expressed hope that Sweden will be brought into the NATO fold by the time allied leaders meet in Lithuania on July 11-12. Stoltenberg met with Erdogan on Sunday in Istanbul for talks but no breakthrough was made.