Joe Biden (Photo: EPA/MICHAEL REYNOLDS)

US President Joe Biden called Donald Trump's a "useful lackey" of dictator Vladimir Putin in a post he wrote on X (Twitter).

Earlier at a campaign rally in South Carolina, Trump said that NATO was bankrupt before he came to power and told how he demanded that allies increase defense spending.

"One of the presidents of a big country stood up and said, ‘Well, sir, if we don’t pay, and we’re attacked by Russia, will you protect us?’ I said, ‘You didn’t pay, you’re delinquent?’ – 'No, I would not protect you. In fact, I would encourage them to do whatever the hell they want. You got to pay. You got to pay your bills," Trump said.

According to Biden, such statements of his predecessor show why supporting Ukraine is important.

"Because as you can see, Putin and his useful lackeys have their eyes on bigger prizes," the American leader said.

A number of US officials believe that after a probable victory in the elections, Trump will appoint people to key government positions who will negatively change the foreign policy of the United States towards China, NATO, and Ukraine.

In addition, the US Congress approved a law that prohibits presidents from withdrawing from NATO without the approval of the Senate or a Congressional act. These are preventive measures based on the concern of the United States and its European allies about the hypothetical leadership of Trump. Analysts believe that Trump, becoming president, can try to withdraw the United States from NATO.

NATO Secretary General Jens Stoltenberg does not believe that the United States will withdraw from the Alliance if Trump returns to the presidency.