US President Donald Trump’s handling of his meeting with Russian President Vladimir Putin was the most “disgraceful” instance of “kowtowing” to foreign leaders by an American head of state, says former US Secretary of State John Kerry.

“I found it to be one of the most disgraceful, remarkable moments of kowtowing to a foreign leader by an American president that anyone has ever witnessed,” Kerry told CBS News on Sunday.

The former top diplomat criticized the Republican head of state for not challenging Putin on the issue of Russia’s alleged meddling in the 2016 US presidential elections.

During a joint press conference after the private meeting in Finland last week, Trump undermined reports by the US intelligence community that Moscow had indeed interfered in the vote through hacking attacks that helped Trump defeat his Democratic rival Hillary Clinton.

The US president also appeared to accept Putin’s explanation that the Kremlin had never meddled in the democratic process of the US. Trump even said he saw no reason why “would it be” Russia behind the alleged cyber attacks. He withdrew that statement a day later, claiming that he meant to say “wouldn’t.”

Kerry said Trump not only “surrendered” himself to Putin but he also showed to the world that the president of the United States was no longer in control.

“It wasn't just that it was a kind of surrender. It's that it is dangerous. The President stood there and did not defend our country. He stood there and did not defend the truth, he did not defend the facts,” Kerry said.

“It's dangerous because it sends a message to President Putin and to the rest of the world that the President of the United States, the leader of the free world, really doesn't have a handle on what he's doing,” he added.

Kerry also rejected Trump’s explanation that he made a grammatical lapse during the meeting.

Trump has been under fire from both sides of the isle for his performance in Helsinki. Even his closest Republican allies think he failed to protect American interests in the meeting.

The president, however, insists that the meeting showed how tough he is on Russia. He has even invited Putin for trip to the White House.