The number of weapons released by U.S. and allied aircraft in Afghanistan sharply spiked in April, hitting the highest point in nearly five years.

According to an airpower summary posted online this week by U.S. Air Forces Central Command, coalition aircraft released 460 weapons last month, more than double the 203 weapons released in March. It was the most in a single month since August 2012, when 589 weapons were released. The only months that came close in recent years were August and September 2014, when 437 and 441 weapons were released, respectively. But most other months saw fewer than 200 weapons released.

In a statement Friday, Navy Capt. Bill Salvin, the public affairs director for the Resolute Support mission, said that the renewed focus on eliminating an Islamic State subsidiary called ISIS-Khorasan is leading the coalition to conduct more offensive operations, which is contributing to the increase in weapons released. Also, Salvin said, this is the first spring fighting season since former President Obama expanded the military's authority to attack Taliban forces last June.

April was also the month when the Air Force dropped a massive GBU-43 Massive Ordnance Air Blast bomb on a network of ISIS-Khorasan tunnels in Nangarhar Province, Afghanistan.

The number of airstrikes against ISIS in Iraq and Syria — part of Operation Inherent Resolve — dropped slightly last month, from a high of 3,878 in March to 3,274 in April. But while that's the lowest number so far in 2017, it's still larger than any single month in the war's first two and a half years. Operation Inherent Resolve began in August 2014.

AFCENT spokeswoman Capt. Kathleen Atanasoff said Friday that the complex nature of the fight against ISIS, and the need to prevent civilian casualties, is why coalition aircraft have eased off slightly on its weapons released.

"In general, the coalition moves at the speed of our partner forces on the ground," Atanasoff said. "Right now, the preponderance of our effort is around Mosul [in Iraq] and Raqqah [in Syria], which are both very dense, difficult battlespaces in which to maneuver. Given that protection of civilians is crucial to the success of this campaign, the coalition is being very deliberate and careful in applying airpower effects in urban battlefields."

Syria, with the Russian military also operating in the area, is a particularly complicated situation, also leading the coalition to exercise caution.

"Following the [Tomahawk missile] strike in early April, we were extremely diligent and methodical in regards to where and when we flew in Syria to mitigate any strategic miscalculations," Atanasoff said.

However, these statistics do not account for all coalition weapons released. AFCENT has previously said that its statistics account for weapons released by aircraft under Combined Forces Air Component Commander, or CFACC, control, which includes aircraft from all U.S. military branches and coalition aircraft. But not all aircraft flying in the area fall under CFACC control.

Military Times also found that potentially thousands of airstrikes, such as strikes conducted over the years by attack helicopters and armed drones operated by the Army, were not included in AFCENT's statistics. This means that the number of weapons released so far this year is likely higher than the statistics show.

The coalition is also dramatically increasing the number of sorties flown in Afghanistan with at least one weapon released this year. By this point in 2016, the coalition had flown 178 sorties with at least one weapon released. But in the first four months of 2017, it flew 312 sorties with at least one weapon released. At the same time, the number of overall sorties flown dropped, from 1,664 in the first four months of 2016 to 1,243 in the first third of 2017.

The same pattern held for Operation Inherent Resolve, though less dramatically. Sorties with weapons released increased from 3,705 in the first third of 2016 to 4,063 in the first four months of 2017, while the number of overall sorties over those periods dropped from 7,943 to 6,415.