In this file image made from a video released Sunday, Feb. 15, 2015, by militants in Libya claiming loyalty to the Islamic State group purportedly shows Egyptian Coptic Christians in orange jumpsuits being led along a beach, each accompanied by a masked militant. (AP Photo, File)

For almost all of its existence, the Islamic State has focused on a spectacular yet singular goal: The creation of a new Islamic caliphate centered around Syria and Iraq. While there were threats and attacks farther afield, these attacks were generally made by groups or individuals with relatively weak links to the Islamic State's core.

On Sunday, Islamic State militants in Libya released a video that showed the gruesome beheading of 21 Egyptian Christians who had been kidnapped in December and January. It claimed to be the first propaganda video from the Libyan branch of the Islamic State, with all the hallmarks of an "official" Islamic State release.

The response to the video has been dramatic, with Egypt bombing what it said were Islamic State positions in Libya, and a remarkable escalation of concern about the Islamic State in Europe. The response was understandable: It seemed like finally the Islamic State was truly stepping outside the caliphate.

Despite the shock of the video, however, it was really just proof of what we already knew: The Islamic State has had a presence in Libya for months. Last October, a number of members of the Darna-based Islamist group "Shura Council for Islamic Youth" pledged fealty to Abu Bakr al-Baghdadi, leader of the Islamic State. Sources told CNN that this branch of the Islamic State now has 800 fighters and that 300 Libyans who had traveled to Syria to fight for Baghdadi have now returned, bolstering these numbers. There are also reports that senior Islamic State figures have visited Libya, lending the offshoot real credibility.

What is the strategic value of Libya for the Islamic State? One worrying answer comes from an unofficial Islamic State letter recently translated by London's Quilliam Foundation. In that letter, which was written by an Islamic State supporter who uses the alias Abu Arhim al-Libim, Libya is described as a "gateway" for the Islamic State, with a “strategic geographic” that “looks upon the sea, the desert, mountains, and six states: Egypt, Sudan, Chad, Niger, Algeria and Tunisia."

Europe, in particular, becomes a viable target for the Islamic State from Libya, which the author notes "has a long coast and looks upon the southern Crusader states, which can be reached with ease by even a rudimentary boat."

That talk of Libya's strategic location has Europeans concerned, nowhere more so than in Italy. The Italian island of Lampedusa lies just over 100 miles from Libya, and Italians already deal with a vast number of refugees floating toward their shores. The country's colonial past in Libya also adds a worrying historical dimension to the situation. Italy, clearly worried, called on the United Nations on Wednesday to tackle the problem in Libya.

The Islamic State's interest in Libya may well be based just as much on opportunism as well as strategy: Libya's ongoing chaos has provided a window of opportunity. "Security in Libya has been deteriorating since 2012," Christoper Chivvis, a senior political scientist at the Rand Corporation, explains in an e-mail, "but the situation grew especially bad over the summer, just as ISIS was making inroads in Iraq, so there is a confluence of events."

There's little central authority in Libya anymore, and, as my colleague Ishaan Tharoor noted this week, major cities such as Darna have a long history of Islamist movements that date back deep into the Moammar Gaddafi era. These Islamist groups have taken over important parts of the country, and, at times, their actions don't look so different from the Islamic State: The Shura Council for Islamic Youth carried out a spectacular and horrific public killing in a soccer stadium months before its members pledged allegiance to Baghdadi.

The vast number of weapons in the country, a result of Gaddafi's large military budget and the recent civil war, are another major factor for the Islamic State. This is something Libim draws attention to in the letter translated by the Quilliam Foundation: “One leak of [these munitions] from Libya to Mali enabled jihadist groups there to take over more than two thirds of the country in a very short amount of time," he notes.

The element of opportunism here doesn't mean that Libya isn't part of a wider plan -- a plan that, importantly, isn't in conflict with its central caliphate. Last month, Aaron Zelin of the Washington Institute for Near East Policy wrote about the Islamic State's "model" for its franchises, pointing out that the group had announced several months ago that it was "annexing" territory in Algeria, Libya, Egypt's Sinai region, Saudi Arabia and Yemen.

As Zelin noted, the announcement brought with it echoes of al-Qaeda's "franchise" groups, which included the likes of al-Qaeda in Iraq and al-Qaeda in the Arabian Peninsula. The crucial difference between al-Qaeda and the Islamic State's strategies, Zelin writes, is that the Islamic State doesn't seem to want its offshoots to try to attack the West like al-Qaeda did. Instead, it hopes they will form their own mini-caliphates.

Most of these "annexed" territories aren't really much to look at so far. The exceptions are Sinai and Libya. Cole Bunzel, an academic who studies the Islamic State, suggests that the horrific video in Libya may be a way of announcing to the outside world the spread of these territories. "A bloody, provocative video in Libya shows the world that it's serious about its gambit here," Bunzel explains. "IS wants these 'provinces' to be seen as full-fledged members of the 'caliphate' with its base in Iraq and Syria."

It's an ambitious plan, but at one point so was the caliphate in Syria and Iraq. Now the Islamic State is following the same model in Libya, Bunzel says. "Then as now, the group announced its expansion to a new territory and gradually began winning recruits and taking territory." Can it succeed again?