U.S. President Joe Biden closed a three-day NATO summit in Washington on Thursday by promising to “keep NATO strong” at a press conference that focused heavily on U.S. politics and concerns about his mental fitness.

The 81-year-old U.S. leader is facing calls to let another candidate from his Democratic Party replace him in this year’s presidential race due to fears that he is suffering a mental decline.

The opposing Republican Party is expected to nominate former president Donald Trump, 78, at its convention, which begins on Monday in Milwaukee, Wisconsin.

“My predecessor has made it clear he has no commitment to NATO,” Mr Biden said. “He’s made it clear that he would feel no obligation to honour Article 5″ of the NATO treaty, which commits all allies to respond if one is attacked.”

Mr Biden added, “But I made it clear a strong NATO is essential to American security. And I believe the obligation of Article 5 is sacred. I will not bow down to Putin. I will not walk away from Ukraine. I will keep NATO strong.” 

Mr Biden’s speech followed a three-day summit in which NATO leaders announced further military support for Ukraine’s efforts to repel the Russian invasion, including air defence systems and a pledge to spend $43 billion in the next year.

They also declared Ukraine’s future path to NATO membership “irreversible.”

The United States and Germany also announced on Wednesday that the former would station long-range cruise missiles in “episodic deployments” in Germany to strengthen NATO’s deterrence in Europe.

However, Mr Biden’s closing press conference was dominated by the forthcoming presidential election in his country and whether he should persist in running for re-election.

When asked whether he would still be able to “deal with” Russian President Vladimir Putin and Chinese President Xi Jinping three years from now, Mr Biden said he would not talk to Mr Putin until the Russian leader changed course.

(dpa/NAN)