Eager to turn the page from questions about his mental fitness, President Joe Biden on Tuesday officially opened NATO's Washington Summit by announcing what he called a "historic donation" of critical new air defense capabilities to bolster Ukraine's fight against Russia.

"Putin wants nothing less -- nothing less than Ukraine's total subjugation, to end Ukraine's democracy, to destroy Ukraine's culture and to wipe Ukraine off the map and we know Putin won't stop at Ukraine," Biden declared. "But make no mistake Ukraine can and will stop Putin."

The commitments Biden outlined include four Patriot anti-missile batteries; the U.S., Germany and Romania will supply one each, and the fourth will be cobbled together from components provided by the Netherland and other NATO members, according to a statement from the countries.

"The United States will make sure that when we export critical air defense interceptors, Ukraine goes to the front of the line. They will get this assistance before anyone else gets it," Biden declared. "All told, Ukraine will receive hundreds of additional interceptors over the next year, helping protect Ukrainian cities against Russian missiles."

Biden's pledge of new help for Ukraine comes as performance on the world stage is being scrutinized amid questions about his political future.

Italy has also committed to providing Ukraine with another of its SAMP-T air defense systems, the joint statement said.

In his address, Biden said NATO allies would also share "dozens" of other tactical air defense system s with Ukraine in the coming months.

Ukraine's President Volodymyr Zelenskyy has been urging NATO allies to fortify the country's air defenses for months, and on Monday, an onslaught of Russian missiles underscored the dire need.

According to Ukrainian officials, the strikes killed 33 people in Kyiv, making it the deadliest attack on the capital city since Russia's invasion began in early 2022.

Zelenskyy has said Ukraine requires seven more Patriot systems, so Biden's announcement only partially fills that demand.

Germany and Romania had previously publicly indicated they would send Patriot batteries to Ukraine. U.S. officials had also confirmed that an American battery stationed in Poland would be transferred, but the move had not yet been formally announced.

Alliance leaders have long anticipated that ensuring Ukraine could continue to weather Moscow's aggression would top the gathering's agenda, but following Biden's fumbling debate performance, the summit has also been cast as a pivotal test of his capability to serve as president for another four years.

In the days leading up to the meeting, White House officials have sought to emphasize Biden's efforts to restore American leadership within the alliance and on the international stage more broadly--contrasting his position with Republican challenger Donald Trump, who has repeatedly threatened to leave NATO.

"An overwhelmingly bipartisan majority of Americans understand that NATO makes us all safer," Biden said. "Americans, they know we're stronger with our friends."

Biden also acknowledged outgoing NATO Secretary-General Jens Stoltenberg, thanking him for his pivotal leadership and honoring him with the Presidential Medal of Freedom, the highest American honor that can be bestowed upon a civilian.