Kamara spent time with the Crew in 2006 and 2007 and Berhalter admitted it was an exciting time for the club to bring back such a player.
"Everyone is excited; the players are excited. And although we're announcing these moves for the future, we're purely focused on today and Saturday," he said.
"That's important. We're not losing sight of where we want to go this season.
"After having conversations with him, we told him about our project and what we were doing and he was on board. He was excited about it."
Berhalter has high hopes for the Sierra Leone international, who has also previously played with San Jose Earthquakes, Houston Dynamo, Sporting Kansas City and Norwich City, and sees him as another strong avenue to goal for his side that sits fifth in the Eastern Conference.
"First of all, I think he's a proven goal scorer in this league," Berhalter added.
"He played wide for Kansas City, but we see him more as a number nine. That's the position he's most comfortable in.
"He's a goal scorer, he's a hard worker, he's a leader, he's good in the locker room. So I think he has a lot of attributes that make him very valuable."
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