Washington (CNN) President Donald Trump made it clear a day after firing national security adviser John Bolton that he will be calling the shots on US foreign policy and possibly changing course.

In wide ranging comments to reporters in the Oval Office on Wednesday, Trump held forth on Iran and Afghanistan, pausing to criticize Bolton for his positions on Iraq and North Korea and make clear he disagreed with his former adviser's stance on Venezuela.

While Bolton pushed tough measures against Iran and North Korea -- and in the past has advocated for the use of military force against both -- Trump praised the potential of both countries and did not rule out easing sanctions on Tehran, a change the regime is demanding before it will engage in talks.

The President hinted at high-level contacts with both Pyongyang and Tehran, saying "those are two countries we're dealing with right now on a very high level," and he declared that talks with the Taliban are "dead."

"That was my decision," Trump said of the move to cancel a Camp David meeting planned for just a few days before the anniversary of the September 11 terror attacks with the militant group that once sheltered Osama bin Laden and al Qaeda -- reportedly a subject of disagreement with Bolton, who disapproved. "And what we're doing now is my decision," Trump said.

The President suggested Wednesday that he isn't necessarily looking into facilitating a meeting with Iranian President Hassan Rouhani at the upcoming UN General Assembly in New York later this month, but left the door open.

"I'm not looking at anything," he said. "I do believe they'd like to make a deal. If they do that's great and if they don't, that's great, too."

Iran and North Korea have 'potential'

Asked whether he'd consider easing sanctions to make a meeting happen, Trump said, "We'll see what happens. I think Iran has potential and I think North Korea has -- those are two countries we're dealing with right now on a very high level."

And he repeated a pledge that might be seen as reassurance for Iran's leaders. "We're not looking for regime change," Trump added.

In his remarks about the Taliban talks, the President emphasized that "we are hitting the Taliban right now harder than they've ever been hit. What they did was horrible."

"They've been hit very hard. I know for a fact they said that was a big mistake that they made, and it was," said Trump, who went on to describe a car bomb attack last week for which the Taliban has taken credit.

"When they killed a great American soldier, when they killed 12 people, innocent people, essentially innocent people because if you look, I mean, many of these people were civilians. You also had a NATO soldier in addition to our great soldier. But what they did in order to create what they thought was a better negotiating stance," he said.

The Taliban has taken responsibility for at least nine US service member deaths in 2019 and likely is responsible for another seven, given the location of those deadly attacks, areas seen having a strong Taliban presence. A total of 16 American service members have been killed in Afghanistan in 2019 and over 2,400 US service members have killed in Afghanistan since 2001.

Trump and administration officials have not explained why the car bomb attack last week resulting in the death of Sgt. Elis Barreto Ortiz tipped the balance and led Trump to cancel the talks.

On Wednesday, though, Trump told reporters that after Ortiz's death, "I said that's the end of them, get them out, I don't want anything to do with them."

Trump also said that he disagreed with Bolton on Venezuela. The Trump administration has thrown its full support behind interim Venezuelan President Juan Guaido and at one point, appeared to back an attempt by the opposition leader to oust embattled President Nicolas Maduro.

"I disagreed with John Bolton on his attitudes on Venezuela. I thought he was way out of line and I think I've proven to be right. I don't want to talk about that," Trump said, without elaborating on the exact nature of the disagreement.

"We have a policy on Venezuela that's a firm policy," Trump went on. "Venezuela's really hurting and we're trying to help in a humanitarian way. That's probably not good in terms of crushing a terrible regime, but you have people dying."

Disagreements with Bolton laid bare

Trump repeatedly returned to Bolton, in part because of reporters' questions.

"John is somebody that I actually got along with very well," the President said of Bolton, "but he made some big mistakes."

Trump pointed to Bolton's talk about "the Libyan model" as a road map for North Korea denuclearization as one misstep.

The "Libyan model" is a reference to a 2003 secret agreement Libyan leader Moammar Gadhafi made with the UK and the US to voluntarily give up nuclear equipment he had purchased from a Pakistani scientist who also sold to Iran and North Korea.

In 2011, when the US joined European military action against Libya, Gadhafi fled and was ignominiously killed by rebels who found him in a ditch. After the allied invasion of Libya launched, North Korea's foreign minister at the time declared that the push for Libya to denuclearize had been "an invasion tactic to disarm the country."

That memory casts a shadow over US negotiations with North Korea today -- and particularly when Bolton raised it in an interview.

"We were set back very badly when John Bolton talked about the Libyan model, and he made a mistake. And as soon as he mentioned that, the Libyan model, what a disaster," Trump said.

"Take a look at what happened with Gadhafi with the Libyan model, and he's using that to make a deal with North Korea? And I don't blame Kim Jong Un for anything he said after that, he wanted nothing to do with John Bolton. And that's not a question of being not tough... that's a question of being not smart to say something like that," Trump said.

He also went after Bolton several times over his role in the 2002 invasion of Iraq, which took place while Bolton was serving under the President George W. Bush administration.

"John is known as a tough guy, he's so tough he got us sent to Iraq," the President commented. "Mr. Tough Guy... you have to go into Iraq. I don't say it was his decision, you had a president and you had other people also, but he was very out there I can tell you."

Trump said he "disagreed with that decision from the very beginning."

"Here we are many, many years later, decades later, and we're still there," he added.

Asked about Bolton's departure, the President said that the longtime Washington operative would likely "do whatever he can to spin it his way," but that he had asked Bolton to resign.

"He sat right in that chair," Trump said, pointing to a chair in the Oval Office, "and I told him, 'John, you've got too many people, you're not getting along with people.' "

He continued, saying he told Bolton, " 'I wish you well, but I'd like you to submit your resignation,' and he did that"