FOXBOROUGH, Mass. -- New England Patriots coach Bill Belichick said that the kicking footballs used in the first half of Sunday's 27-17 loss to the Kansas City Chiefs were "underinflated by 2, 2 pounds," and he deferred to the NFL as to why that was the case for both teams.

"We don't have anything to do with it. Were we aware of it? Yeah, definitely," Belichick said. "As I understand it, they were all the same. I don't know what the explanation is. It was the same for both teams.

"You'd have to talk to the league about what happened on that. That part of it, they control all that."

MassLive.com first reported on the underinflated kicking footballs. Per league rules, the kicking footballs are supposed to be between 12.5 and 13.5 pounds per square inch, with officials in charge of ensuring that is the case as they are in possession of all footballs leading up to the game.

Referee Shawn Hochuli's crew worked the Chiefs-Patriots game Sunday in Foxborough. Hochuli is in his 10th season working NFL games and was promoted to referee in 2018.

A spokesperson for the NFL declined comment regarding the underinflated footballs.

Belichick said missed field goals by Kansas City's Harrison Butker (39 yards) and New England's Chad Ryland (41 yards) in the first half, and two kickoffs that almost went out of bounds, were plays in which "you could see" how the underinflated footballs affected the game.

Patriots players privately acknowledged that it was disappointing that the footballs weren't pumped correctly, but noted it was the same for both teams. Ryland, who is enduring a challenging rookie season with 13 field goals in 20 attempts, appeared to be notably frustrated in the locker room after the game.

Butker had made all 23 of his field goal attempts entering the game but didn't think his 39-yard miss was a result of the air pressure in the football.

"I think it was technique, one of those misfires that you wish you had back," he said. "My second kick of pregame warmup, I had a 38-yarder middle, and it kind of sliced off to the right like that. So it showed up, kind of, in warmup. I made a lot of big kicks with flatter balls, and shoot, even in college, I kicked a lot of flat balls."

Butker, 28, is in his seventh NFL season and said he couldn't tell that the footballs were underinflated. He said that officials informed him at halftime that "the balls were a little deflated" and "they just let me know they pumped [them] up."

He described that process as "nothing new" and "kind of routine."

Butker made a 29-yard field goal early in the third quarter and that's when he first felt something different.

"I didn't notice anything on that opening kickoff and then second half, once you make that [field goal], you have the kickoff and you can feel the ball," he said. "And it was noticeably more pumped up. But again, cold weather is going to make the inflation go down. ...

"I've even had games where the bladder of the ball might pop or something, and maybe you feel it on kickoff and then you just ask for a different ball. So stuff like that happens and you just roll with it. I've made decent kickoffs with balls that maybe aren't perfect 13 PSI indoor room temperature, but it's just kind of the nature of the game. Sometimes that stuff happens."

The inflation level of footballs was a major NFL story when the Patriots were ultimately fined $1 million, docked two draft picks, and quarterback Tom Brady was suspended four games for what the NFL determined was a scheme to provide improperly inflated footballs for the AFC Championship Game against the Indianapolis Colts on Jan. 18, 2015.

As a result, the NFL put strict protocols in place to ensure footballs used in games were inflated properly.

ESPN's Adam Teicher contributed to this report.