Manchester United confirmed the Argentine's appointment on Friday, bringing an end to Michael Carrick's spell as head coach and securing Pochettino on a two-and-a-half-year contract until June 2029.
The move comes despite Pochettino having signed an extension with US Soccer that was intended to keep him in charge through to the 2030 World Cup. He will nevertheless complete the United States' two upcoming matches against Haiti before taking up his new position at Old Trafford.
Speaking at a press conference in Atlanta alongside US Soccer chief executive JT Batson and president Cindy Parlow Cone, Pochettino explained how quickly the situation had developed.
"We cannot underestimate the people in the business. When things start to become bigger and bigger the players are aware, but the staff are also sensitive.
"They started to feel something, too. All [that happened] was so quick. We arrived here last Friday. Sunday afternoon, this type of situation started to appear. There was some contact. We were very transparent; we started talking to JT [Batson, US Soccer CEO] and the federation.
"Yesterday [Thursday], when the talks were positive with the agreement, we had a meeting with the players and whole staff. I wanted to say thank you because they were so supportive and really understood the situation. They know us and how committed we have been.
"They support us for the next two games. Then the agreement between US Soccer and Manchester United, we continued with our job in the camp. We have time next week to talk about the job in Manchester United. Now I want to talk about us and the national team."
The emotional impact of the decision became clear as Pochettino struggled to hold back tears. He had taken charge of the United States in September 2024 and had developed a strong relationship with the players and federation during his time in the role.
He was particularly keen to acknowledge the supporters and the people who had helped him during the past two years.
"I want to thank the fans for their support, for everything," he said. "Always when you arrive at these type of moments, they're tough. It's not an easy decision. Normally it is the opposite. You get sacked and you cry as you want to stay!
"In the same time, we are excited for that next step forward. Now is not the moment to talk, to be committed. We really care and we are always going to care about the federation and the people that are here. Many things happened in the last two years and we have always shown commitment.
"We are focused on the next two games. The players are amazing and they know how to manage these types of situations. It is not ideal but like in life, football moves so quick. We need to move forward and keep all the memories that we shared."
Pochettino was asked why he had signed a new agreement with US Soccer if he remained open to returning to club management in Europe. His response was that the opportunity to take charge of a club of United's stature was simply too significant to turn down.
"It is obvious," he replied. "I never said I wanted to go back. They know that there are not too many opportunities in your career with a club the size of Manchester United. When that arrives, it is difficult to turn down that situation.
"What I want to make clear, when we decided together to extend our commitment, maybe something could have happened in a different way. Maybe new people arrive and they have different ideas and say: 'OK, Mauricio: now you need to go home.'
"We were very committed. We never thought it happened too [this] quick."
US Soccer chief executive Batson paid tribute to the outgoing coach, highlighting the work he and his staff had done beyond the results achieved by the national team.
"Mauricio has left a lasting mark on US Soccer through his leadership, professionalism and commitment to our players and culture," Batson said.
"What we are most proud of goes beyond the wins. He and his staff raised standards, strengthened our culture and created clearer connections from the youth national teams to the senior team.
"Those changes are now embedded in how we operate, and we will keep building on them as we pursue sustained success on the world stage."
Pochettino's immediate responsibility is to complete the United States' Nations League quarter-final against Haiti before travelling to England. He is expected to begin work at United on November 18, with his first match scheduled to be the visit to Liverpool.
The scale of the task awaiting him is considerable. United are 18th in the Premier League and need a rapid improvement in results, but Pochettino has made clear that his attention will remain with the United States until his final international commitments are complete.