(CNN) Turkey's President refuses to rule out the death penalty for thousands of people arrested after a failed military coup Friday , despite warnings that reintroducing capital punishment could dash Turkey's chances of joining the European Union.

Speaking through his translator in an exclusive interview with CNN's Becky Anderson, Turkish President Recep Tayyip Erdogan called the failed military coup a "clear crime of treason."

The Turkish people have made it clear they want death for the "terrorists" who plotted the coup, Erdogan said in his first interview since the July 15 attempt.

"The people now have the idea, after so many terrorist incidents, that these terrorists should be killed, that's where they are, they don't see any other outcome to it," he said.

"Why should I keep them and feed them in prisons, for years to come? That's what the people say," he said. "They want a swift end to it, because people lost relatives, lost neighbors, lost children ... they're suffering, so the people are very sensitive and we have to act very sensibly and sensitively."

The comments come in the wake of the President's vow over the weekend that those responsible "will pay a heavy price for this act of treason."

A total of 8,777 officers from the Turkish Ministry of Interior have so far been removed from office, according to the state-run Anadolu news agency.

At a mass detention in Ankara, dozens of detainees were forced to kneel partially stripped.

Among the arrested are 103 generals and admirals, a third of the general-rank command of the Turkish military.

It would take a parliamentary decision in the form of a constitutional measure to make the death penalty an option, Erdogan said.

"Leaders will have to get together and discuss it and if they accept to discuss it then I as President will approve any decision that comes out of the parliament," he said.

Turkey abolished the death penalty for peacetime crimes in 2002, followed by a total ban in 2004 as part of a series of human rights reforms undertaken for its membership bid for the European Union.

If Turkey does reintroduce the death penalty, it won't be joining the European Union , EU foreign policy chief Federica Mogherini said earlier Monday.

Within 12 hours, 'the results we wanted'

Erdogan said he was on vacation with his wife, son-in-law, and grandchildren in the resort town of Marmaris when he was informed on Friday that there was "some kind of movement" in Istanbul, Ankara and other cities.

With his family and a few "very close people" from his inner circle he followed recommendations to move to a safer location by plane.

While they were in the air, the air traffic control tower at Istanbul's Ataturk Airport was under the control of soldiers attempting the coup, he said. Upon discovering the airstrip lights were turned off, he and his pilots considered landing using onboard lights.

Forces loyal to Erdogan retook the air traffic control tower and the plane was able to land, Erdogan said, but they soon heard booms.

"Starting from the moment we landed, F-16s started flying above us, very close to the ground," Erdogan said.

As tanks rolled through the streets of the capital, Ankara, and Istanbul, Erdogan said he addressed the nation via FaceTime because the national TV broadcast was not reaching people's televisions.

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Speaking through a CNN Turk anchor who held her phone so viewers could see it, he urged people to stand up to the military faction behind the uprising.

"Go to the streets and give them their answer."

Throughout the ordeal it "never crossed my mind" that he would no longer be President, he said.

Within 12 hours the coup had been foiled and the government had "the results we wanted," he said.

The "invaders" would be dealt with quickly.

Erdogan rejected any claims that he would use the attempted coup, considered an act of terrorism by his government, as justification for a crackdown against his opponents.

Erdogan said he and his government had to do the "right thing" and that an "oppressive figure" would never have received 52% of the popular vote, a reference to his win in the 2014 presidential election.

He added that he has "no issues" when it comes to a free press. But, if there are media outlets that sided with and supported the plotters of the attempted coup, the justice system would need to take steps, he said.

Extradition a 'mutual agreement'

With arrests made in Turkey and eight soldiers who fled to Greece awaiting extradition, Erdogan addressed the status of Turkish cleric Fethullah Gulen, who is in self-imposed exile in the United States.

Fethullah Gulen

Erdogan has previously blamed Gulen for the attempted coup, a claim that Gulen has denied.

A formal written request for the extradition of Gulen will be submitted within days, Erdogan told Anderson.

When asked what he would do if the United States refused to extradite Gulen, he said "we have a mutual agreement of extradition of criminals."

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"So now you ask someone to be extradited, you're my strategic partner, I do obey, I do abide by that, but you don't do the same thing -- well, of course, there should be reciprocity in the types of things," the President continued.

U.S. Secretary of State John Kerry said the United States hadn't yet received a formal request from Turkey for Gulen's extradition.