“If Trent Alexander-Arnold is not in the squad then England must have an extremely good squad,” said Klopp.
“I was surprised when he didn’t get the call-up. I respect the decision, of course I do. But I didn’t understand it.
“I am a manager myself, I make decisions every day, every weekend, every midweek about team selections and squad selections.
“We always make decisions that other people probably do not understand.
“I respect that Gareth makes his own decisions, of course, but I didn’t understand it anyway because Trent Alexander-Arnold was in the last two seasons at least, let me say the season before and the season before that, the stand out right-back in world football – that is the truth and at an unbelievable young age.
“He started the season with Covid and you can imagine it took him a while to get into the season, but from the moment when he was in the season he was one of our most consistent players and a stand-out player.
“He could play all the time, high level all these types of things, so that cannot be the reason that he was not in the squad.”
Alexander-Arnold has been one of a number of Liverpool players to draw scrutiny for a loss of form during their struggle in defending the Premier League title.
The Reds – champions by 18 points last season – sit seventh this term, 25 points behind leaders Manchester City.
They face a trip to Arsenal in the Premier League on Saturday.