The United States must tackle some concerning mentality issues, which are to blame for their defeat to Canada.

That is the view of interim coach Mikey Varas, who has few answers for solving the problem.

USA were beaten 2-1 by Canada in Kansas City on Saturday, in their first game of the post-Gregg Berhalter era.

It marked Canada's first victory on US soil in 67 years.

And while Mauricio Pochettino reportedly waits in the wings to take over the Stars and Stripes, Varas hit out at the team's mentality.

"The mentality is on the players. They know it," he told reporters.

"We speak the truth to each other. I love those guys. But they know that mentality to fight, to run and to sacrifice, I can't do that for them. That's on them.

"I'm not a psychologist, so I don't know. I felt that the training [sessions] were intense. They were aggressive.

"But when the game comes, you gotta get going. And the players are the ones that bring that. Coaches can only get you so far from a mentality perspective."

Varas did shoulder some of the blame, too, suggesting he may have tried to introduce too many new ideas, too soon.

"I think on the ball, that's on me," he said.

"I want to present some ideas to them and you just never know how it's going to translate from training to the game after three training sessions. And I asked a lot of them, you know, and if there's a goal, I mean, that's on me.

"When you don't have a lot of time to work and you want to play a certain way it creates confusion.

"Players are going to take responsibility for quality of action. The translation of the ideas wasn't clear enough because you shouldn't be static and you shouldn't pass the ball just to pass the ball. You're trying to be trying to accelerate play as quickly as you can."