(CNN) President Donald Trump said in an interview broadcast Sunday night that Russian President Vladimir Putin is "probably" involved in assassinations and poisonings, but "it's not in our country."

"Of course they shouldn't do it," the President added.

Trump's remarks came during a wide-ranging interview on CBS's "60 Minutes" that touched on his relationship with North Korea, China, Russia, and his own West Wing staffers and Cabinet.

When asked by CBS' Lesley Stahl about the accusation that he is leery of criticizing Putin, he challenged the question.

"I think I'm very tough with him personally. I had a meeting with him, the two of us," Trump said, referring to his much-criticized summit with the Russian leader in which he declined at a press conference to endorse the US government's assessment that Russia interfered in the 2016 presidential election. "It was a very tough meeting, and it was a very good meeting," Trump told Stahl.

Here are 10 other key moments from the interview.

Russian interference in the 2016 election

Asked after his Putin comments whether he thought Moscow meddled in the 2016 presidential election, Trump said he didn't think it was just Russia.

"They meddled. But I think China meddled, too. And I think other countries ..." Trump said. He added, "And I think, frankly, China is a bigger problem."

On James Mattis' politics and future in the White House

When asked whether Defense Secretary James Mattis would be leaving his post at the Pentagon, Trump said he was unsure.

"Well, I don't know," he said, adding, "He hasn't told me that." Trump said the two maintained "a very good relationship," but he allowed for the possibility Mattis would leave.

"I think he's sort of a Democrat, if you want to know the truth," Trump told Stahl. "But Gen. Mattis is a good guy. We get along very well. He may leave. I mean, at some point, everybody leaves. Everybody. People leave. That's Washington."

China trade

The President said he "might -- might" -- impose more tariffs on China

While the United States has now imposed $250 billion in tariffs, Trump last month threatened to impose even more tariffs if China retaliates against American farmers or other industries.

"They want to negotiate ... they want to negotiate," the President said.

When asked if he was ready to negotiate, Trump responded, "I have a great chemistry ... with President Xi (Jinping) of China. I don't know that that's necessarily going to continue. I told President Xi we cannot continue to have China take $500 billion a year out of the United States in the form of trade and other things ... and I said we can't do that, and we're not going to do that anymore."

Trump said he was not trying to push China into an economic depression.

"No, no, although they're down 32% in four months, which is 1929," the President said. He added, "I don't want that. ... I want them to negotiate a fair deal with us. I want them to open their markets like ... our markets are open."

North Korea

When pressed by Stahl over his embrace of North Korean leader Kim Jong Un , Trump said he knew about Kim's human rights violations, but that his efforts have resulted in fewer threats to the United States.

"Sure. I know all these things. I mean, I'm not a baby. I know these things," he said.

The President continued," Look, let it be whatever it is. I get along with him really well. I have a good energy with him. I have a good chemistry with him. Look at the horrible threats that were made. No more threats. No more threats."

Mueller investigation

Asked if he would pledge to refrain from interfering in special counsel Robert Mueller's investigation , Trump refused, but continued his refrain of "no collusion."

"I don't pledge anything," Trump said. "But I will tell you, I have no intention of doing that. I think it's a very unfair investigation because there was no collusion of any kind."

When pressed on not pledging, the President replied, "There is no collusion. I don't want to pledge. Why should I pledge to you? If I pledge, I'll pledge. I don't have to pledge to you. But I have ... I have no intention of doing that."

On family separations at the border

Trump and Stahl reached an impasse when he refused to give her a straight answer on whether or not he would resume enforcement of his administration's "zero tolerance" immigration policy that led to family separations at the southern border. Instead, the President told Stahl that former President Barack Obama also maintained the same policy. When he later cited Obama again, Stahl changed subjects, leading Trump to claim that she was being unfair to him.

"I'm just telling you that you treated me much differently on the subject," Trump said, comparing the media's treatment of him to Obama's.

"I disagree, but I don't want to have that fight with you," Stahl responded.

"Hey, it's OK," Trump said.

"All right, I'll get in another fight with you," Stahl said, again attempting to change subjects.

"Lesley, it's OK. In the meantime, I'm President, and you're not."

On Melania Trump's comments there are untrustworthy aides at the White House

"I feel the same way. I don't trust everybody in the White House, I'll be honest with you," Trump said.

"I'm usually guarded," the President added. "And I think I'm guarded anyway. But I'm not saying I trust everybody in the White House. I'm not a baby. It's a tough business. This is a vicious place. Washington, DC, is a vicious, vicious place. The attacks ... the bad-mouthing, the speaking behind your back. But, you know, and in my way, I feel very comfortable here."

Life in politics

Asked what he has learned and what he was most surprised by since becoming President, Trump, who never held political office before entering the White House, bemoaned the political atmosphere in Washington.

"So I always used to say the toughest people are Manhattan real estate guys and blah, blah. Now I say they're babies," Trump said.

Asked who is the toughest, the President said, "The political people. This is the most deceptive, vicious world. It is vicious, it's full of lies, deceit and deception. You make a deal with somebody and it's like making a deal with -- that table."

Climate change

Asked if he thinks climate change is a hoax , Trump said, "I think something's happening. Something's changing, and it'll change back again. I don't think it's a hoax, I think there's probably a difference. But I don't know that it's man-made. I will say this. I don't want to give trillions and trillions of dollars. I don't want to lose millions and millions of jobs. I don't want to be put at a disadvantage."

Trump added that he is not denying climate change, "But it could very well go back. You know, we're talking about over a million ... years. They say that we had hurricanes that were far worse than what we just had with Michael."

Pressed about scientists who have said climate change is worse than ever, Trump said, "You'd have to show me the scientists because they have a very big political agenda."

On mocking Kavanaugh accuser Christine Blasey Ford at a Mississippi rally

"I will tell you this. The way now Justice (Brett) Kavanaugh was treated has become a big factor in the midterms. Have you seen what's gone on with the polls?" Trump said.

Asked if he believes he treated Ford with respect, the President said, "I think so, yeah. I did."