Ankara, Turkey (CNN) A week before the formal opening of the US Embassy in Jerusalem , Turkish President Recep Tayyip Erdogan described the decision to move the office as a "huge mistake."

Speaking exclusively to CNN in Ankara on Tuesday, Erdogan said that there was "nothing to gain" by the move and urged the US to reverse the decision while there was still time to do so, repeating his claim that "East Jerusalem is the capital city of Palestine" and will one day be home to an embassy serving Turkey's interests in a Palestinian state.

He also said that the decision had contributed to isolating the US diplomatically. Pointing to the United Nations vote in December , when 128 countries condemned the decision and just nine supported it, Erdogan said: "The United States is losing true friends right now."

'The US will lose in the end'

During the interview, which took place shortly before Trump announced the US withdrawal from the Iran nuclear deal , Erdogan also leveled strong criticism at the US on its approach to the Iran treaty, on allegations of "hostage diplomacy" and on interventions in Syria.

Echoing the position of many world leaders outside the Middle East, Erdogan criticized the US for abandoning the Iran deal, insisting that "you should respect an agreement that you have signed," and said he feared "new crises" would break out as a result.

He also said the move would jeopardize the global economy. "The United States might gain some certain positivity out of the withdrawal...or the rising oil prices, but many of the countries in poverty will be hit even harder and deeper."

By reimposing sanctions on Iran, Trump is declaring "an economic war" that the world can ill afford, the Turkish leader said.

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When asked if he has concerns of a geopolitical war breaking out as a result, he said: "That's not what we would wish to see, of course ... this is not what we'd like to expect. However, in my view, the US would be the ones to lose. Iran will never compromise on this agreement, and will abide by this agreement to the end ... that's what I think. However, the US will lose in the end."

Asked directly what he thinks about the US President, Erdogan said only that "as politicians, we need to abide by the boundaries of mutual respect."

US is 'giving weapons free of charge to terrorists'

Erdogan's negative remarks about US policy speak to the growing tensions between the two nations. While they retain an important military alliance, their relations have become increasingly frayed as Erdogan has consolidated political power and aligned himself more closely with US foes such as Russia and Iran.

The NATO allies have sparred over a slew of issues in recent years, with added friction coming from the continuing conflict in Syria.

In January, Turkey launched an assault on Afrin , a town in northern Syria controlled by a US-allied group of Syrian Kurds called the YPG, which Turkey says is an arm of a designated terrorist organization that threatens Turkish sovereignty. US officials say Turkey's military offensive there undermines the fight against ISIS.

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Speaking on Tuesday, Erdogan accused the US of giving weapons "free of charge" to members of the YPG and the Kurdish Democratic Union Party (PYD), whom Erdogan described as "terrorists."

He also criticized Trump directly for rejecting Turkey as a "strategic partner" in Syria.

"Let's fight together in Raqqa, was what I said to President Trump personally," Erdogan said. "And stop supporting PYD and YPG. Don't walk hand in hand with these terrorists or that'll be a mistake. But unfortunately, the US preferred moving with them and set aside Turkey."

He also defended a series of trilateral meetings involving Turkey, Russia and Iran on Syria that have been widely criticized and boycotted by a number of Western countries and Syrian groups. "We're taking strong steps forward," Erdogan said.

The Turkish-US relationship has been further strained by Turkey's detention of North Carolina pastor Andrew Brunson , who was arrested in 2016. Trump has repeatedly called for the missionary's release.

Erdogan said Brunson is undergoing a fair judicial process in Turkey and "is not a hostage." He accused the US of politicizing a judicial matter and questioned instead why the US was refusing to extradite Fethullah Gulen, an exiled cleric living in Pennsylvania whom the Turkish government accuses of being behind a failed coup attempt in July 2016.

"He's being harbored there. And he's not a convict. He's not even being detained," Erdogan said of Gulen. "And we demand his extradition, and he's not being extradited to us. But there is a Pastor Brunson here, who is being currently prosecuted -- and he's allegedly associated with terrorist organizations. And you're asking for him?"