Republican presidential candidate Donald Trump on Wednesday praised Russian President Vladimir Putin, saying he had been "more of a leader" than US President Barack Obama.
Trump, who spoke during a televised forum, said he had great respect for the Russians and would have "a wonderful relationship" with Putin.
"I think I'll be able to get along with him," Trump said. "He's been a leader. Far more than our president has been a leader."
He said the advantage of the United States having a good relationship with Russia was that Moscow wanted to destroy Islamic State as badly as the US did.
"Wouldn't it be wonderful if we could work on it together?" he said. "Wouldn't that be a wonderful thing?"
He also said Putin had "very strong control" over his country, adding that it was a very different political system that he didn't like.
The forum was held in New York before a live audience and broadcast on prime time television by NBC News.
Democratic candidate Hillary Clinton also took part in the event, which was framed as an opportunity for the two candidates to speak about the US president's role as commander-in-chief.
Clinton was grilled about her use of a personal email server while she was secretary of state and her handling of classified information. She defended her behaviour, saying she did "exactly what I should have done."
She also said if elected she would not send ground troops into Iraq or Syria.
"We are going to defeat ISIS without committing American ground troops," she said.
The two candidates were not on stage simultaneously. They each faced questions from members of the audience and from the host of the programme.
The first presidential debate, when the candidates of the two leading parties will face off, is scheduled to take place on September 26.