WASHINGTON: US President Joe Biden has said that he has "no good reason" to talk to Vladimir Putin at the moment unless the Russian leader changes his behaviour.

The 81-year-old president made these remarks on Thursday at a highly-anticipated solo press conference at the end of the NATO Summit in Washington.

“I have no good reason to talk to Putin right now. There's not much that he is prepared to do in terms of accommodating any change in his behaviour, but there isn't any world leader I'm not prepared to deal with,” Biden told reporters when asked if he is ready to talk to Putin.

“But I understand your generic point is, is Putin ready to talk? I'm not ready to talk to Putin unless Putin's ready to change his behaviour and the idea -- look, Putin's got a problem," Biden said, dismissing concerns about his health despite a growing list of Democratic leaders urging him to step aside from the 2024 presidential election following last month's disastrous debate with his Republican rival, Donald Trump.

"First of all, in this war that he supposedly has won, and by the way, I think, don't hold me to the exact number, but I think that Russia had 17.3 per cent of Ukraine that they've conquered, now it's 17.4. I mean, in terms of percentage of territory,” he said.

“They've not been very successful. They've caused horrible damage, and loss of life, but they've also lost over 350,000 troops, military, killed or wounded. They have over a million people, particularly young people with technical capability leaving Russia because they see no future there. They've got a problem,” said the president.

“But what they do have control of is they are very good at controlling and running the public outcry that relates to how they use mechanisms to communicate with people. They lie like hell to the constituencies. They lie like hell about what's going on. So the idea that we're going to be able to fundamentally Change Russia in the near term is not likely,” he told reporters.

“But one thing for certain. If we allow Russia to succeed in Ukraine, they're not stopping in Ukraine...I'm prepared to talk to any leader who wants to talk, including if Putin calls me and wants to talk. The last time, I talked to Putin was trying to get him to work on an arms control agreement related to nuclear weapons and space. That didn't go very far,” he said.

“So, my point is I'm prepared to talk to anybody, but I don't see any inclination. There is an inclination on the part of the Chinese to keep in contact with me because they're not sure where this all goes. Look what's happened in Asia. We have strengthened the Asian-Pacific area more than anyone else has,” he said.

“I asked our NATO allies that we bring on the group from the South Pacific, Australia, New Zealand, Japan, Australia. I've met twice now, with the 14 leaders of the Pacific island nations, and we've slowed down what's going on there. We've slowed down China's reach. But there's a lot of work to do. This is a moving target, and I don't take it lightly,” Biden said.

He used the press conference to deliver a forceful defence of his foreign and domestic policies and batted away questions about his ability to serve another four years, declaring, "I'm not in this for my legacy. I'm in this to complete the job."

There have been concerns about Biden's ability to serve another four-year term as president since his stumbling performance in a presidential debate opposite Donald Trump last month.

Age and mental fitness have recently become a major issue in the US presidential race.

While the issue has troubled President Biden, and his Republican rival Trump, 78, in the past, things reached a tipping point after Biden's disastrous debate performance last month.

While Biden is the oldest president in US history, Trump, if elected in November, would be the second oldest.