Vice President Biden speaks to students, faculty and staff at Harvard University's Kennedy School of Government in Cambridge, Mass., on Oct. 2. (Winslow Townson/AP)

During a question and answer session at Harvard University’s Kennedy School of Government last week, Vice President Biden somehow managed to anger some of the U.S.'s most vital allies in the fight against Islamic State.

Biden has now apologized to both the United Arab Emirates and Turkey for the comments, but to anyone who has been following the conventional wisdom in foreign policy circles, it's not surprising that he would think this privately (even if it is surprising that he would say so publicly).

To understand why, it helps to take a look at exactly what Biden allegedly said. When asked by a student whether the United States should have acted earlier in Syria, Biden first explains that there was "no moderate middle" in the Syrian civil war, before changing the topic to talk about America's allies:

"Our allies in the region were our largest problem in Syria. The Turks were great friends, and I have a great relationship with Erdogan, [who] I just spent a lot of time with, [and] the Saudis, the Emirates, etcetera.

What were they doing? They were so determined to take down Assad, and essentially have a proxy Sunni-Shia war, what did they do? They poured hundreds of millions of dollars and tens of tons of weapons into anyone who would fight against Assad – except that the people who were being supplied, [they] were al-Nusra, and al-Qaeda, and the extremist elements of jihadis who were coming from other parts of the world.

Now, you think I'm exaggerating? Take a look. Where did all of this go? So now that's happening, all of a sudden, everybody is awakened because this outfit called ISIL, which was al-Qaeda in Iraq, when they were essentially thrown out of Iraq, found open space and territory in [eastern] Syria, [and they] work with al-Nusra, who we declared a terrorist group early on. And we could not convince our colleagues to stop supplying them.

So what happened? Now, all of a sudden – I don't want to be too facetious – but they have seen the lord. Now we have ... been able to put together a coalition of our Sunni neighbors, because America can't once again go into a Muslim nation and be the aggressor. It has to be led by Sunnis. To go and attack a Sunni organization. And so what do we have for the first time? [Audio cuts out]"

At this point, the White House recording cuts out. Other accounts, however, suggest he went further. According to Hurriyet Daily News, Biden also said:

President Erdoğan told me, he is an old friend, said you were right, we let too many people through, now we are trying to seal the border.

Biden's comments have prompted a furious reaction from Erdogan, who denied ever making such a statement, demanded an apology and called his relationship with the vice president "history." Meanwhile, the UAE expressed "astonishment” at Biden's accusations.

The vice president's comments may be a "gaffe" in diplomacy – and, yes, his comments do reveal a worrying habit of lumping al-Qaeda's al-Nusra Front in with Islamic State and not noting the difference between private and public funding at play here. But there are genuine, though complicated, concerns at the heart of this gaffe.

Below, we take a look at some of the key criticisms of America's Middle East allies.

Turkey

While Turkey was not one of the initial U.S. partners in strikes against the Islamic State, it is a key NATO member in the region and recently voted in favor of expanding its military role in Syria and Iraq.

However, reporting by The Post and other outlets suggests that at the outset of the Syrian war, the Turkish government was keen to facilitate fighters in Syria with the hope of destabilizing Bashar al-Assad's Syrian regime. "Wounded jihadists from the Islamic State and the al-Nusra Front [...] were treated at Turkish hospitals," The Post's Anthony Faiola and Souad Mekhennet reported in August. "Most important, the Turks winked as Reyhanli and other Turkish towns became way stations for moving foreign fighters and arms across the border."

While Faila and Mekhennet report that Turkey later worked to close the border, there are reports that Islamic State supporters now have a foothold in Istanbul and other parts of the country. Ankara recently secured the release of 49 hostages from the Islamic State, which has led to suspicion and theories about what the Islamic State may have gotten in return, further complicating Turkey's relationship to the extremists.

“Turkey in many ways is a wildcard in this coalition equation,” Juan Zarate, a senior adviser at the Center for Strategic and International Studies, told the New York Times this week. “It’s a great disappointment: There is a real danger that the effort to degrade and destroy ISIS is at risk. You have a major NATO ally, and it is not clear they are willing and able to cut off flows of funds, fighters and support to ISIS.”

United Arab Emirates

The second party offended by Biden is in fact a key partner in the strikes against the Islamic State, and had proudly publicized the role its first female fighter pilot had played in the bombing campaign against the extremist group.

However, the UAE has long been linked to support for rebel groups in Syria: In 2012, the Swiss government temporarily halted arms exports to the country after a Swiss-made grenade exported to the emirates was photographed in the possession of Syrian rebels. In 2013, the government had to step in to help block private donations to jihadists in the country, The Post's Joby Warrick reported.

Saudi Arabia

Saudi Arabia is another key ally in the fight against Islamic State, yet it has also been criticized for alleged ties to the group. "I accuse them of inciting and encouraging the terrorist movements," Iraq's then-Prime Minister Nouri al-Maliki told French television this year. "I accuse them of supporting them politically and in the media, of supporting them with money and by buying weapons for them."

Saudi Arabia was clearly providing funding for moderate Syrian rebels in 2012, though a year later it cracked down on private donations after it emerged that many were going to Islamist groups. It is not believed to have funded the Islamic State or other extremists directly, and while private funding from the country may have been important for the Islamic State a few years ago, its importance has diminished over time.

"Although Saudi donors and other private contributors were believed to be the most significant funding source for the original forerunner to ISIS," Lori Plotkin Boghardt wrote in an analysis for the Washington Institute in June, "the importance of such donations has been marginalized by the group's independent sources of income."

What may be more significant is the number of Saudi citizens who have traveled to Syria to fight. One recent report from the Soufan Group cited Saudi figures that 2,500 citizens had traveled to become foreign fighters in Syria.

Qatar

While not specifically mentioned by Biden, Qatar is an ally in the fight against the Islamic State who has also been accused of supporting them. "You have to ask who is arming, who is financing ISIS troops," German Development Minister Gerd Mueller said in an interview with broadcaster ZDF in August. "The keyword there is Qatar — and how do we deal with these people and states politically?"

According to a 2013 estimate from the Financial Times, the tiny, oil-rich country had put as much as $3 billion into funding anti-regime Syrian rebels, far more than any government. As The Post's Rajiv Chandrasekaran reports, U.S. officials have said that while they do not believe Qatar funded extremists groups directly, its tactics for funding the rebels were sloppy and unsophisticated, and Qatar may have inadvertently helped the group in some way.

"So has Qatar funded Islamic State?" Michael Stephens, director of the Royal United Services Institute in Qatar Directly, wrote for the BBC recently. "The answer is no. Indirectly, a combination of shoddy policy and naivety has led to Qatar-funded weapons and money making their way into the hands of IS."

Kuwait

While not an ally in strikes against the Islamic State, Kuwait has long been a regional ally of the U.S. However, while it has avoided funding Syrian rebels directly, it is accused of not doing enough to stop private funding that may well have reached extremists in Syria.

"There is evidence that Kuwaiti donors have backed rebels who have committed atrocities and who are either directly linked to al-Qaeda or cooperate with its affiliated brigades on the ground," said a December 2013 report from the Brookings Institution. Kuwaiti sheiks such as Hajjaj al-Ajmi were successful at using social media to compel significant donations from the public, The Post's Joby Warrick noted last year.

"Donors have taken advantage not just of Kuwait’s poor legal framework," Elizabeth Dickenson wrote late last year for the Carnegie Endowment for International Peace, "but also of its pluralistic political environment, where free assembly and private charities are permitted."