WASHINGTON — The Air Force's first F-35 squadron has completed all preparations necessary to declare the joint strike fighter combat capable, and sources say an initial operating capability declaration could be made early next week.

Twelve jets have received the modifications necessary for IOC, 21 combat-mission-ready pilots are available, and the maintenance infrastructure is ready to support the Hill Air Force Base's 34th Fighter Squadron, said some of those operators on July 27. With paperwork filed, all that's left is for Air Combat Command head Gen. Herbert "Hawk" Carlisle to sign off.

"We have achieved all our milestones," said Lt. Col. Steven Anderson, deputy commander of the 388th Maintenance Group. Anderson, along with several other maintainers and pilots from Hill Air Force Base, spoke to reporters over a conference call. "We have submitted all of the data to ACC for General Carlisle's consideration on making that declaration."

Over the past couple of weeks, pilots at Hill finished up the last remaining items on its IOC checklist, said Lt. Col. George Watkins, 34th Fighter Squadron commander. For instance, the Air Force considers pilots "combat mission ready" only after he or she complete a certain number of training sorties during a 30- or 90-day period, so some operators had to conduct additional flights.

"As of today, we have 21 pilots combat mission ready based on the number of training sorties they've done in the last 30 days," he said. "That was one thing that was yellow."

They also went through "pilot verifications," which Watkins described as similar to an oral examination. After doing an in-depth study of the F-35's mission systems, tactics and potential threats, pilots briefed a panel, who then quizzed the pilots on a simulated mission.

The Air Force has laid out several requirements for declaring the F-35A ready for battle. It needs at least 12 combat-configured F-35As with enough trained pilots, maintainers and other personnel needed to support the jets. The aircraft must be deployable and able to conduct basic close-air support, air interdiction and limited suppression and destruction of enemy air defense missions.

Hill Air Force Base has received 15 F-35As, and expect another to be delivered in August, Anderson said. Twelve jets have gone through modifications necessary to make them ready for combat, including improvements to the fuel system, additional lightning protection and a modification that expands the flight envelope of the aircraft.

All of the aircraft have installed the latest software, which fixed previous software instability issues, he said.

An early IOC declaration would be no surprise given Carlisle's own statements on the matter. The ACC commander told reporters earlier this month to expect a declaration during the "leading edge" of the Aug. 1 through Dec. 31 window for IOC.

Even though the version of the aircraft's logistics system planned to be ready for the milestone, Autonomic Logistics Information System (ALIS) 2.0.2, will not come online until this fall, Carlisle has said that would not be a "limiting factor" on his decision.

The recent deployment of seven F-35As to Mountain Home Air Force Base, Idaho, proved the current version meets requirements for the aircraft to operate away from home base, he said. During that event, Hill Air Force Base pilots conducted exercises and maintainers serviced the plane using a deployable version of ALIS.

"We've deployed with the current software we had and it worked," Carlisle said. "The Marines have deployed with it in its current configuration. It's not quite up to where we wanted to be, but there's workarounds."

Past precedent is another indication a decision could happen early in August. The Marine Corps, which declared their jets combat-capable last year, wrapped up final tests of the aircraft and filed the paperwork necessary for IOC on July 27, 2015. Chairman of the Joint Chiefs of Staff Gen. Joe Dunford — then the Marine Corps commandant — signed off on the jets days later, on July 31.

Twitter: @ValerieInsinna