The United States military confirmed early Tuesday morning that, in conjunction with five Arabic nations, it had begun bombing the Islamic State of Syria and Iraq (ISIS) inside Syria.

At the bottom of the press release from U.S. Central Command (CENTCOM), two paragraphs explained that in addition to targeting ISIS, U.S. bombs had also hit a group that nobody had even heard of just a couple weeks earlier: Khorasan.

At a Pentagon press conference Tuesday morning, Lieutenant General William Mayville said the U.S. had been monitoring Khorasan closely.

"We believe the Khorasan group is -- was nearing the execution phase of an attack either in Europe or the homeland," Mayville said. "We know that the Khorasan group has attempted to recruit Westerners to serve as operatives or to infiltrate back into their homelands."

The general added that it was too early to describe the effects of the eight air strikes against Khorasan, or say who may have been killed.

U.S. officials told CBS News last week that Khorasan is a unit with a mandate directly from al Qaeda's central command in Pakistan, sent into Syria with bomb-making experts from the terror network's affiliate in Yemen, to try and plot attacks against the U.S. and Western allies.

"I think it's important that the fight against ISIS has now gone to Syria," Mike Morell, former deputy director of the CIA, said Tuesday, "but I think it's even more important that we struck the Khorasan group last night."

Morell, who is now a CBS News contributor, noted on "CBS This Morning" that CENTCOM had said it was attacking Khorasan to due to "imminent threat plotting" by the group.

"That's what we were trying to disrupt," Morell said. "What that means to me as an intelligence officer, it means that we had detailed intelligence on attack plotting, either in the United States, or in Western Europe, or in both."

CENTCOM said only that it had targeted Khorasan "training camps, an explosives and munitions production facility, a communication building and command and control facilities" to the west of the sprawling frontline city of Aleppo.

The military's press release made it clear that the strikes against Khorasan "were undertaken only by U.S. assets" -- in other words, no help from the five nations which joined in the fight against ISIS, or any other regional allies.

Khorasan does not function as an independent group on the Syrian battlefield. It is part of or at least directly linked to al Qaeda's franchise in the country, known as the al-Nusra Front, and as CBS News correspondent Clarissa Ward reports, attacking it may bring repercussions.

Unlike the attacks on ISIS, "airstrikes against Nusra are not likely to be very popular on the ground," Ward said on "CBS This Morning."

"Although both espouse the same extremist ideology, Nusra has large support among the Syrian population, and has actually been fighting against ISIS on the battlefield -- at times even alongside the Western-backed, so-called 'moderate' rebels that the U.S. is hoping will fight this war," explained Ward.

She said American strikes against al-Nusra could "put those U.S.-backed fighters in a very tough situation, because they simply do not have the weaponry or the manpower to fight the Assad regime and ISIS, and now potentially the Nusra Front as well, at the same time."

The U.S. State Department made it clear that as far as the Obama administration is concerned at least, a strike on Khorasan is not the same as a strike on al-Nusra.

CBS News correspondent Margaret Brennan reported that, according to State Department officials, there is "some" overlap between al-Nusra and Khorasan, but they are not one in the same.

A Department official told Brennan that Khorasan refers to a network of al-Nusra Front and al Qaeda extremists and their associates who share a history of training operatives, facilitating fighters and money, and planning attacks against U.S. and Western targets.

Early Tuesday, Syrian activists said airstrikes overnight had killed as many as 50 al-Nusra fighters in rural Idlib province, which lies to the west of Aleppo. It remains unclear who carried out the strikes -- with some witnesses saying they were U.S. missiles and others saying it was Syria's own military, on the orders of President Bashar Assad.

At least one senior al-Nusra commander was reportedly among the dead in Idlib province.

It was not immediately clear whether the U.S. government told its Arab allies in advance -- some of whom participated directly in the strikes against ISIS -- that American firepower was also going to be directed at members of Khorasan.

In addition to causing possible angst among the "moderate" rebels who are being bolstered by new infusions of U.S. cash and weaponry, the strikes against Khorasan -- if perceived to be strikes against the wider al-Nusra group -- could also raise eyebrows among key U.S. allies in the Gulf region.

While all Arab states deny funding or supporting terrorist groups, there have been many reports suggesting oil-rich Sunni Muslim governments, including Qatar's, have given their tacit approval for donations to groups including al-Nusra for years, eager to shore-up the fighters on the ground deemed most capable against the Shiite Muslim Assad regime.

Qatar is not alone. CBS News' Wyatt Andrews reported earlier this month that U.S. officials have focused on private donations as a revenue stream to jihadist groups in Syria, including ISIS.

The U.S. has complained, but the Gulf states have internal reasons for allowing the donations to continue, said Andrews.

"In Kuwait, some of terrorist fund-raisers are very powerful and popular, and the government is very concerned about upsetting this domestic constituency," former U.S. intelligence analyst Lori Plotkin Boghardt told CBS News. "The irony is that some of America's closest allies in the Gulf allow their citizens to support terrorist groups."

The U.S. has slapped sanctions on some Gulf citizens in recent months for funneling money to extremist groups in Syria.