American refueling planes rumble into the air from this desert air base around the clock to top up coalition aircraft bombing Islamic State militants, whether they're Arab fighters flying out of regional bases or French warplanes catapulted off an aircraft carrier in the Persian Gulf.

The al-Udeid Air Base in Qatar is the regional nerve center for the air war against the militants who have taken over nearly a third of Iraq and Syria. That makes it the main hub for coordinating warplanes from the U.S. and 11 other nations in the coalition carrying out bombing raids.

While the U.S. is doing the heavy lifting in the airstrikes, American officials say the allies' contributions are vital.

"This is dangerous stuff. This is not political theater," said Lt. Col. David Haworth, chief of the current operations division for the Combined Air Operation Center.

"I don't think what we are doing today would be even remotely possible without the coalition partners," he told The Associated Press, making a rare media visit to the base. "To say that we want to or we are capable of going it alone I think would be a terrible mistake."

The low-rise Combined Air Operation Center, packed with rows of computer terminals overseen by big-screen monitors, brings together officers from across the coalition to help share information and plan missions.

Intelligence gathered by coalition members helps give commanders a deeper understanding of how the Islamic State group operates on the ground, Haworth said. For example, at times its fighters mass together like a traditional army unit, while in other situations they behave more like insurgent guerrillas.

All information will be key in preparations for an eventual offensive by Iraqi troops and Kurdish fighters to retake the northern Iraqi city of Mosul, the biggest city under the extremists' control. The coalition will no doubt be backing the assault, though officials here would not discuss plans for future operations.

"If they (the militants) want to try and reinforce, whether it's Mosul or some other location, we want to make sure we're ready," Haworth said. "If they want to flee, we'll want to make sure that we have that contingency covered as well."

American planes in general hit more of what the military refers to as "dynamic" targets — ones that are not pre-planned — and a mobile insurgency like the Islamic State group makes for a lot of dynamic targets.

The Air Force estimates that half of all strikes in the battle stem from close air support for Iraqi ground forces. Another 30 percent involve hitting Islamic State militants traveling between Iraq and Syria.

Many coalition members, meanwhile, might drop multiple bombs on a single preset target, such as a militant-held compound or mobile oil refinery.

Since the bombing campaign began, American warplanes have handled 80 percent of the 2,780 airstrikes carried out as of Tuesday in Iraq and Syria, according to the most recent figures provided by the U.S. military.

Primarily Western allies including Australia, Belgium, Britain, Canada, Denmark, France, Jordan and the Netherlands operate over Iraq, and have handled about three of every 10 airstrikes there.

The share of American strikes is even greater in Syria. There, Arab coalition members have conducted just 93 airstrikes, compared with 1,137 by American aircraft. The countries operating alongside the U.S. over Syria include Bahrain, Jordan, Saudi Arabia and the United Arab Emirates.

By the military's definition, an airstrike refers to a particular target, regardless of how many planes are involved in hitting it and how much ordnance is fired at it. By another measure — strike sorties — three out of five times that a warplane takes off on a strike mission in the campaign, it's an American plane. Or by yet another measure, other coalition members have dropped a fifth of the munitions used so far in the campaign.

Part of the reason for the large American role in Syria comes down to the monthslong battle for Kobani, where relentless pounding from the air helped Kurdish fighters finally fend off the Islamic State group's offensive trying to take the town, on the border with Turkey.

Longer-range American aircraft like the swept-wing B-1 bombers that operate out of al-Udeid were particularly well suited for that fight. They are able to spend hours over the battlefield loaded with up to 24 tons of bombs that can be used in multiple airstrikes.

"We brought a lot of loiter time, a lot of weapons" over Kobani, said Lt. Col. Joe Kramer, 34th Expeditionary Bomb Squadron commander.

The number in Syria was also affected by the Emirates' decision to sit out the fight for several weeks after Jordanian fighter pilot Lt. Muath al-Kaseasbeh went down behind enemy lines in December. He was eventually killed by the militants.

The UAE, which boasts one of the region's most capable air forces, resumed airstrikes last month after the U.S. moved search-and-rescue teams closer to the battlefield. It and Bahrain have deployed some aircraft to Jordan, bringing them closer to the fight.

Arab allies also give the coalition access to much-needed bases dotted around the Gulf. Canadian warplanes operate out of Kuwait, for example, while Australia has deployed F/A-18 fighters to an air base outside Dubai.

In addition to Qatar, American planes fly out of bases in the Emirates, Kuwait and Jordan, as well as off the carrier USS Carl Vinson.

Al-Udeid also hosts a forward headquarters for U.S. Central Command, which directs military operations throughout the region, including those still ongoing in Afghanistan, as well as Patriot missile batteries to protect regional allies against missile attacks.

The base continues to grow: New ramp space to handle additional American aircraft opened just last month, and more dormitory buildings are being raised. A second runway is under construction.

Without other countries' support, the coalition would not be able to sustain as many missions and would have less intelligence on militants' operations on the ground, officials say.

Even less-heralded tasks such as refueling bombers and fighters — a crucial mission because of the long distances aircraft need to fly from bases outside the combat zone — would be harder without the allies' help.

"To look at just strikes would be like to look at a baseball game of just home runs," Haworth said, describing the battlefield intelligence and other resources coalition members bring as "not just wanted, but necessary."

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