President Barack Obama is outlining plans Wednesday for an expanded military and political effort to combat the group in Syria and Iraq, ushering in what is likely to be a long-term engagement by the U.S. and its allies to destroy the militants in those countries.
It is useful to remember, though, that while it is a formidable force that controls roughly a third of Iraq and Syria, there also has been an inclination to exaggerate the group's capabilities.
"I think sometimes there's been a tendency to sort of overestimate the technical sophistication of the Islamic State," said Charles Lister, visiting fellow at the Brookings Doha Center.
Lister, like many other analysts, said much of the power of the Islamic State group — also known by the acronyms ISIS or ISIL — lies in its centralization of command and intense loyalty within the organization.
That distinguishes the group from others, which are overstretched by years of conflict. In the case of the Syrian rebels, there are deep divisions that have hampered their cause.
Militants from the Islamic State group have waged an aggressive social media campaign. They have released statements with detailed information on conquests and battles, and posted high-quality videos that often provide visual proof of their activities in regions that have suffered a media vacuum recently as the risks have become too great for journalists.
In Syria, two American journalists were beheaded by the group in the past month. The killings, posted on militant websites, were shot in high definition, featured embedded soundbites from Obama, and used wireless microphones to amplify statements from the masked, English-speaking militant and his victims.
According to a senior Iraqi intelligence official, more than 27,600 Islamic State fighters are believed to be operating in Iraq, about 2,600 of whom are foreigners.
Most analysts, however, estimate the number of Islamic State fighters in both Iraq and Syria to be about 20,000.
In any case, the group is dwarfed by its foes in the Syrian and Iraqi armies — both in numbers and firepower.
The Iraqi military and police force are estimated at more than 1 million. The Syrian army is estimated at 300,000 soldiers. There are believed to be more than 100,000 Syrian rebels, including the al-Qaida-linked Nusra Front and the powerful Islamic Front rebel umbrella group, currently fighting the Islamic State group in Syria. Tens of thousands of Kurdish Peshmerga forces are fighting the group in Iraq.
The Islamic State group's greatest shortcoming is that it lacks the means to fight airpower, meaning that U.S. airstrikes can go a long way in destroying its capabilities.
Still, the Islamic State group has amassed a significant amount of weapons and hardware captured from Iraqi and Syrian military installations in recent months.
The Iraqi official, who declined to be identified because he is not authorized to brief the media, told The Associated Press that the group's arsenal includes Kalashnikovs, machine guns, anti-aircraft guns and mortars, adding that they also have about 35 Iraqi military tanks, about 80 armored police vehicles and hundreds of Humvees.
In addition to those, the group earlier this year paraded in its Syrian stronghold of Raqqa what appeared to be a Scud missile, although it is unclear if the group has the capability to launch it.
Richard Brennan, an Iraq expert with RAND Corporation and a former U.S. Department of Defense policymaker, said the Islamic State group has captured 155mm howitzers — artillery weapons the Iraqi army commanded. It also captured some old Soviet-era tanks. They also seized some heavy weapons, including 50-caliber machine guns.
The group has a few MiG 21s captured when it overran the Syrian army's air base in Tabqa last month. Analysts say it is extremely unlikely that they could get any of them off the ground at this point.
"It's a very nice thing for them to be able to show in the video. But for now, we're unlikely to see an Islamic State air force anytime soon, or even just one working jet," Lister said.
A study released this week by the London-based Conflict Armament Research said Islamic State group fighters have also amassed weapons supplied by the U.S. and other allied countries, including anti-tank rockets, by overrunning stocks belonging to mainstream Syrian rebels.
Theodore Karasik, a security and political affairs analyst at the Dubai-based Institute for Near East and Gulf Military Analysis, estimated the Islamic State can claim about 20,000 core fighters, and up to 30,000, if allied Sunni tribesman are included.
Islamic State militants have shown the ability to operate commercially available drones, such as one that provided video over Islamic State group-occupied Fallujah.
Perhaps just as important as what the group has acquired is its technical know-how, according to Karasik.
"The main fact is they are very smart and they probably read every manual that the U.S. has put out on air doctrine and special operations doctrine, so they know what's coming," he said.
Among the group's most significant capabilities to emerge in the last six weeks or so, Lister said, has been the group's ability to deploy artillery.
The group has acquired M46 130mm field cannons from bases overrun recently in Syria's Raqqa province. These weapons add to the U.S. M198 howitzers the group captured in Iraq.
"Those are quite significant in terms of adding to the organization's ability to bombard targets before they assault, and that does appear to have been fairly significant in terms of at least weakening a target before launching a ground assault," he said.
A recent report published by the Institute for the Study of War described the Islamic State group as "an institution comprised of many layers of tactical, operational, and strategic capability, and it is expertly led."
"ISIS has a critical capability to design military campaigns that outmatch those of rival militaries in Iraq and Syria, but those military strategies can be overmatched by U.S. strategists, planners and advisers," it added.
Salama reported from Baghdad. Associated Press writers Ryan Lucas in Beirut, Qassim Abdul-Zahra in Baghdad and Adam Schreck in Dubai contributed to this report.
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