Story highlights Vice President Joe Biden apologizes to the UAE

He had said at Harvard that allies inadvertently strengthened ISIS

Turkey's President Recep Tayyip Erdogan demanded an apology from Biden

Biden said Erdogan told him that Turkey had let too many foreign fighters through the border

U.S. Vice President Joe Biden has apologized to the United Arab Emirates and Turkey for comments he made last week that Middle Eastern allies are partly to blame for the strengthening of ISIS.

The latest apology came in phone call from Biden to the Crown Prince of Abu Dhabi, Mohammed bin Zayed Al Nahyan, representatives from both countries said Sunday. The vice president issued an apology to Turkey earlier during the weekend.

The problem appears to have originated during an appearance last week at the John F. Kennedy School of Government at Harvard University when Biden spoke about Turkey, the UAE, other Middle Eastern allies, and the threat posed by the so-called Islamic State terror group, also known as ISIS or ISIL.

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Biden told attendees that the militant Islamist group had been inadvertently strengthened by actions allies took to help opposition groups fighting against Syrian President Bashar al-Assad.

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"They poured hundreds of millions of dollars and thousands of tons of weapons into anyone who would fight against Assad. Except that the people who were being supplied were al-Nusra and al-Qaeda and the extremist elements of jihadis coming from other parts of the world," Biden told students.

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"We could not convince our colleagues to stop supplying them," he said.

On Turkey's alleged role, Biden said, "President (Recep Tayyip) Erdogan told me, he's an old friend, said, 'You were right. We let too many people (including foreign fighters) through.' Now they are trying to seal their border," he said, according to transcripts.

Denial and consternation

Erdogan vehemently denied ever saying such a thing.

Biden extended a mea culpa on Saturday to the Turkish President.

The apology came hours after Erdogan expressed his anger over the comments to reporters in Istanbul, saying, "Biden has to apologize for his statements."

Otherwise, he said, Biden will become "history to me," according to published reports by the semi-official Anadolu news agency.

The United Arab Emirates' foreign ministry hit Biden with a sharply formulated statement Saturday, expressing its "astonishment" at the vice president's remarks.

They were "far from the truth, especially with relation to the UAE's role in confronting extremism and terrorism and its clear and advanced position in recognizing the dangers, including the danger of financing terrorism and terrorist groups," said Minister of State for Foreign Affairs Dr. Anwar Mohammed Gargash.

The apologies

The UAE on Sunday said that Biden apologized to the Crown Prince during their phone call "for any implications in his recent statements" that the Middle Eastern nation has backed the growth of terror groups.

A statement from Biden's office avoided the word "apology," but said he "clarified that his recent remarks regarding the early stages of the conflict in Syria were not meant to imply that the UAE had facilitated or supported ISIL, Al Qaeda, or other extremist groups in Syria."

Biden thanked the UAE for its role in fighting ISIS and terrorism in the region, according to accounts from both nations.

He made similar overtures to Turkey.

"The Vice President apologized for any implication that Turkey or other Allies and partners in the region had intentionally supplied or facilitated the growth of ISIL or other violent extremists in Syria," Biden spokeswoman Kendra Barkoff said.

"The Vice President made clear that the United States greatly values the commitments and sacrifices made by our Allies and partners from around the world to combat the scourge of ISIL, including Turkey."

During their telephone conversation, Biden and Erdogan reaffirmed the two countries' commitment to fight the terror group, Barkoff said.

Erdogan's office and the Turkish Foreign Ministry did not immediately respond to a CNN request for comment regarding Biden's apology.

The issue has arisen at a sensitive time, with Turkey's government authorizing the use of military force against terrorist organizations, including ISIS, as the militant group's fighters laid siege to towns just south of the Turkish border.

The government also agreed to allow foreign troops to launch operations against ISIS from Turkey.

Until now, Turkey has offered only tacit support to the coalition.

While Biden is known for making blunt statements that sometimes embarrass the administration, Turkey is particularly sensitive to allegations of allowing terrorists to cross its border into Syria.

Syrian President Bashar al-Assad has accused Turkey of looking the other way and, in some cases, providing support to rebels embroiled in the country's civil war.

Turkey, in turn, has accused Syria of fomenting the unrest that has led to ISIS taking hold in the region.