Remember when al Qaeda publicly rejected the then-stateless Islamic State of Iraq and Syria for disobeying its orders, but partially also because the militants' predilection for beheadings and crucifixions was a little too much even for them?

As it turns out, al Qaeda leaders might have jumped the gun with their squeamishness. They now want to be friends again — and the international Islamist network may be using the US and its allies' air strikes on the Islamic State as an opportunity to make amends.

That, at least, is what a number of analysts tracking fundamentalist groups in the region and the world are observing, and the prospect of a rekindled friendship between the fundamentalist group of the year and that of the decade has had US officials worried for a while.

Al Qaeda is saying, "Let's just have a truce in Syria," Tom Joscelyn, who tracks terror groups for the Long War Journal, told the AP, referring to fighting between Islamic State militants and the al Qaeda-backed Nusra Front, with which they actually have quite a bit in common. "That is what's underway now... What we have seen is that local commanders are entering into local truces. There are definitely areas where the two groups are not fighting."

A truce in Syria seems to make sense for Islamic State militants, spread thin across multiple fronts as in addition to Syrian forces, Nusra fighters, and other rebel groups, they are now engaged in a bloody battle with Syrian and Iraqi Kurds aided by Western weapons and airpower. In fact, opportunistic truces have been a part of the Syrian Civil War for awhile, where the many groups fighting each other have also frequently formed and dissolved partnerships of convenience.

"De facto truces have been around for some time between the Islamic State and other jihadi groups in Syria," Aymenn Jawad al-Tamimi, who has extensively researched Syrian and Iraqi militant groups, told VICE News. "For example, most of the jihadi groups outside of Jabhat al-Nusra, like Jabhat Ansar al-Din for instance, have done everything possible to avoid getting directly involved in the Qaeda-IS dispute and avoid getting into a situation where they end up fighting IS on the ground."

"Also in Qalamoun, Nusra and IS have been working together since January as part of an initiative of 'different politics but same end goal of a caliphate'," he added.

But a reconciliation would be as symbolic globally as it is strategic in Syria, and on that front in particular there's a lot in it for al Qaeda as well, analysts suggest.

"You are looking at this group that's making headways, it's got the attention, it has land, it has resilient funding sources, it attracted fighters from 80 countries and is at the vanguard of global jihad, so you can't ignore it," Tom Sanderson, co-director of the Transnational Threats Project at the Center for Strategic and International Studies, told VICE News. "If you denigrate it in any way, you are denigrating a group that stands for many of the same principles that the al Qaeda core does.

"At a certain point it becomes sort of self-defeating for al Qaeda to continue to hammer ISIS," he added. "As time goes on they see the reality that these guys are the center of gravity of violent extremism for Sunni jihadis and they are left with no choice but to support them."

On its end, al Qaeda can boost the Islamic State with its own network of fighters, many more experienced and knowledgeable than the younger Islamic State ones, and with its own established connections to funding sources and intelligence.

That has Western observers more than worried. While US officials have long entertained the possibility of a reconciliation, now that that seems closer, they worry about an al Qaeda/Islamic State's coalition capability to hit targets beyond the region.

"If they made a declaration that they are back together and a united front, they would then have to demonstrate relevancy, and they would conduct attacks, I'm sure," Sanderson said.

Internal fighting — particularly between Islamic Sate and Nusra members — has turned off some prospective recruits, is breeding disillusion among fighter ranks, and has drawn the condemnation of a number of Islamist scholars.

Latest among them was Abu Muhammad al-Maqdisi, considered one of al Qaeda's most influential spiritual guides. Al-Maqdisi, a mentor of al Qaeda's late leader Abu Musab al-Zarqawi, had previously denounced the Islamic State, accusing its members of "smearing the reputation" of global jihadist movements with their brutality.

But following recent US-led strikes on the group, he softened his stance and joined the chorus calling for reconciliation within jihadi ranks. He was arrested in Jordan earlier this week — after spending five years in jail on various terrorism charges — and accused of using the internet to incite terrorism.

"Don't rejoice when one side or the other suffers from the aggression of crusaders," Maqdisi wrote in a recent letter.

Calls for a united jihadi front have also come from al Qaeda affiliates elsewhere in the Middle East, including more recently when the group's Yemen-based offshoot denounced US airstrikes and called on rival groups to stop their infighting for the sake of fending off their common enemy, the AP reported.

The image of a divided front is also confusing and discouraging potential recruits, Matthew Levitt, director of The Washington Institute's Program on Counterterrorism and Intelligence, told VICE News. And while flocks of fighters have left the Nusra files to join with the Islamic State holding their ground in Syria, doubts are beginning to seep into both groups.

"A lot of people who have gone to fight, foreign fighters in particular, have been extremely disillusioned by jihadi-on-jihadi-fighting," Levitt said. "It's not in the least surprising that we are seeing appeals for people to have some kind of reconciliation."

But that may not be so easy. From the beginning, there was also a lot more to the breakup between al Qaeda and what is now the Islamic State than their different levels of gruesomeness.

ISIS was originally born as an Iraq-based al Qaeda offshoot, but its leadership found refuge in the political vacuum of power created by years of fighting in neighboring Syria. There, al Qaeda was already backing the work of some rebels fighting the regime of Bashar al-Assad, but as ISIS grew to be one of the most powerful players in the region, they also became less willing to follow the directives of al Qaeda's core leadership.

"Even more than their methods, the main issue was their refusal to heed the commands of Ayman al-Zawahiri," Levitt said, referring to al Qaeda's current leader. "When Zawahiri said, 'you have two different al Qaeda affiliated elements fighting in Syria, and I want Jabhat al Nusra to be my element in Syria, and I want al Qaeda in Iraq [ISIS] to return to Iraq,' Baghdadi said 'No.'"

"The void created in Syria was a godsend for al Qaeda in Iraq, or the Islamic State in Iraq, as they were known at the time," he added. "There they were able to resurrect, and when they rebuilt their capabilities, they of course went and crossed back into Iraq."

It's not clear that the Islamic State ever accepted al Qaeda's call to make amends. It's also not clear that a call was formally extended from the group's core leadership to start with.

But boosted by some tactical successes, the Islamic State's leadership, and al-Baghdadi in particular, might not be all that willing to relinquish authority. The group has already won pledges of support from groups as far away as Boko Haram in Nigeria and some Taliban in Pakistan — though critics predict its popularity will only last so long as they are able to hold on the caliphate they established.

"I don't think he feels the need to compromise with anybody," Levitt said, speaking of al-Baghdadi. "He is the caliph, end of the discussion, you either accept or you don't, and that applies to any individual in the world including Ayman al-Zawahiri."

In fact any partnership with groups not submitting to its authority might raise some existential questions for the group.

"I don't think a true reconciliation is possible because it would negate the Islamic State's raison d'etre, which is that it is a self-proclaimed caliphate demanding allegiance from all Muslims," al-Tamimi said. "There's no allowance for maintaining an independent group, rather one must subsume oneself under the caliphate."

"They also want to maintain the image that they do lead the global jihadi movement," Sanderson added. "They're certainly not going to come under the al Qaeda leadership and take orders from it. At most they're going to see themselves as collegial."

That might eventually change. "The reality on the ground may make him shift," Levitt said. "When you have many, many religious figures — radical jihadis, not just the more moderate figures — saying that there should be reconciliation, that there should be no Muslim fighting Muslim, jihadi fighting jihadi, that may take a toll."

What may also take a toll is the impact of coalition strikes Islamic State leaders insist are not affecting their capabilities in any serious way.

"Some people will be very quick to say that ISIS has the upper hand because events have gone their way, but now that the international community is beginning to step up and is confronting them, I think that its success is at a minimum going to be slowed if not rolled back," Levitt said. "And since much of its support has come from its success, I think it's going to begin to lose some of its allure."