The United States' men's national team wore orange wristbands in support of tighter gun control.
It came after the team sent a letter to Congress calling for "stronger gun laws" following several mass shootings in the country in recent weeks.
Gun control legislation is expected to be voted on by the US House of Representatives.
Berhalter was proud of his team.
"It's easy to get caught up in what we're doing and forget about what's going on outside, but this group certainly didn't do that," he said.
You could see the letter and the orange wristbands. Being the change is something we've been part of for a long time, and it's good that this group is asking for action and asking people to make change.
The letter was signed by players and staff and urged Congress to support stronger gun laws.
"As athletes who have the privilege of traveling the globe representing the greatest country in the world, we are often asked how in a place like the United States there can be such horrible gun violence," the letter said.
The representatives of the people are being asked why they don't do anything. When we return home to a place where mass shootings are frighteningly common and the victims are often defenceless children, we don't experience any of these things.
The ability to affect change is limited, but yours is not.
You can vote this week to address gun violence in America. There are several bills that the US House of Representatives is going to vote on in the coming days. All the bills are being considered, so please vote yes.
Speaking after Sunday's friendly, US defender Walker said "We want to be a team that takes action and has a response, and for the guys to unanimously step up and say no, we approve this letter, it just makes me proud."
It shows our growth as men, as United States citizens, at that level. I'm proud of the group for standing up for what they think is right.
The Golden State Warriors and Boston Celtics wore "End Gun Violence" t-shirts before the second game of the NBA Finals, as part of the "Wear Orange Weekend" campaign.
American tennis player Coco Gauff wrote "Peace - end gun violence" on a camera lens after reaching the final at the French Open.
There have been at least 241 mass shootings in the US so far this year.