NATO allies are in final negotiations over language that says Ukraine's eventual admission into the military alliance is "irreversible" − so long as it makes a series of reforms required for membership.

The U.S. and other member nations agreed at last year's summit in Lithuania that Ukraine would become a member "when Allies agree and conditions are met."

This week they are likely to acknowledge at a critical summit in Washington that, while Ukraine still has a ways to go, as long as it continues to make progress, there will be a path to NATO membership, a U.S. official said.

NATO Secretary-General Jens Stoltenberg told reporters Sunday evening in Washington, D.C., that allies are close to agreeing on precise wording.

"We are working on the exact language on how to express that Ukraine is going to become a NATO ally, and how we are moving forward," Stoltenberg said.

The discussion over NATO membership for Ukraine follows claims from former President Donald Trump, the presumptive 2024 Republican nominee, that he would move quickly to end the war in Ukraine if he is elected in November. Trump has also suggested that talk of Ukraine joining the alliance is provoking Russia.

NATO allies plan to announce a new package of support at this week's summit, which will bring the leaders of more than 31 western nations, including Ukrainian President Volodymyr Zelenskyy, to Washington for several days of talks.

It is likely to consist of five components, Stoltenberg said: training for Ukrainians with a command center in Germany and logistical hubs in the eastern part of the alliance; a financial pledge to continue providing a "minimum baseline" of $43 billion in combined military support over the next year; the delivery of more weapons, ammunition and a "substantial" increase in air defense capabilities; bilateral security agreements, like the 10-year pact the U.S. announced last month; and new programs to help Ukraine's armed forces become fully interoperable with NATO.

The five measures "constitute a bridge to membership" along with language in a summit declaration that expresses that Ukraine is "coming closer to NATO membership," he said.

"The language on membership is one of the remaining issues," Stoltenberg acknowledged. "So we are negotiating that now. I'm confident we will find a solution."

The speaker of Ukraine's parliament, Ruslan Stefanchuk said Monday morning in an exclusive interview with USA TODAY that Ukraine needs more air defense systems, ammunition and fighter jets.

"This is a very powerful package and also the same goes for the bilateral security agreements that Ukraine has already signed with a number of countries," he said. "But one thing we must understand is that this package needs to be the package that supports Ukraine on its path to joining the NATO, but not as a replacement to joining the NATO."

A senior administration official told reporters on a White House call last week that the summit communique would include "very strong language" that amplifies President Joe Biden's position that Ukraine will join NATO.

On Sunday evening, a U.S. official told USA TODAY the Biden administration had agreed to the inclusion of the word "irreversible" on the specific condition that Ukraine meets all the necessary requirements.

For the U.S. to approve Ukraine's membership to NATO, the war with Russia would have to be over and Ukraine would have to enact additional anti-corruption reforms, a second official said.

Stefanchuk says Ukraine has made those reforms. As speaker of parliament, he said he would do everything possible to accelerate the process.

"We are open to all the proposals and suggestions from our partners that will help us not only with fighting the corruption but also with building and strengthening the Ukrainian statehood," he added.

Ukraine a focus of the NATO summit

NATO is taking over the coordination of security assistance to Ukraine from the United States. The goal is to "create a more predictable, robust institutional framework for support" in the long term, Stoltenberg said.

Trump has repeatedly claimed he could end the war quickly if he beats Biden.

“They’re dying, Russians and Ukrainians,” Trump said during a CNN town hall in May 2023. “I want them to stop dying. And I’ll have that done – I’ll have that done in 24 hours.”

Trump said during a presidential debate with Biden on June 27 that, if he wins a second term, he would end the war before he takes office. He did not offer any specifics on how he would end the conflict. Russian President Vladimir Putin later said he believes Trump is sincere, but he did not know what Trump planned to do.

Trump hasn’t said exactly how he would approach the issue. One proposal floated by his allies would involve delaying Ukraine’s entry into NATO and sitting down with Russia.

Under such a scenario, Ukraine would be warned it would get more U.S. weapons if it agrees to enter peace talks, while Russia would be told that refusing to negotiate would result in increased U.S. support for Ukraine.

"This is a time to sit down and start talking," said retired Lt. Gen. Keith Kellogg, who was chief of staff to the National Security Council in the Trump administration.

To Ukraine, the U.S. should say, "If you sit down and talk, we will continue to support you and, if not, we will modify our support," said Kellogg, who's close to Trump and talks to his campaign regularly.

The message to Russia should be, "If you sit down and talk we can stop the killing and discuss Ukraine's near-term admission to NATO. If you do not start discussion, we will support Ukraine to a much greater level to support the destruction of the Russian army in Ukraine."

Other analysts question the wisdom of such an approach.

Rose Gottemoeller, who served as NATO deputy secretary general during the Trump administration, warned that approach would send the wrong message not only to Putin, but to leaders such as China’s Xi Jinping and North Korea’s Kim Jong Un.

“It would send a message that aggression is rewarded,” said Gottemoeller, who is now a lecturer at Stanford University in California. “That's the wrong message an American president wants to send, full stop, to anyone in the world. I think it's a way of tempting violence, aggression in other parts of the world.”

Telling Ukraine it can’t join NATO and telling Russia it can keep some of the territories it has stolen would guarantee a future Russia-Ukraine war, said John Herbst, who served as U.S. ambassador to Ukraine under George W. Bush and is now the senior director of the Atlantic Council’s Eurasia Center.

“The man who put that package together, Trump, would look like a patsy,” he said.

Herbst said such an approach also would impact U.S. interests in the West Pacific.

“It’s no accident that Japan, South Korea and Taiwan have stressed the importance of defeating Putin in Ukraine as a way to deter Xi in Taiwan,” Herbst said. “The stakes go beyond European security and Americans’ critical interest in European security,” he said.

Regardless of the language on membership, allies will announce concrete actions at NATO, Stoltenberg said Sunday.

"The substance of our package, we will deepen and strengthen our security cooperation with Ukraine, it speaks as loudly as language in the declaration," Stoltenberg said. "And I really believe that we now are turning a corner, given that we are able to agree (on) all these elements of the security package."