MARSEILLE, France -- When news first broke of Canada's Olympic soccer team being caught using a drone to spy on an opponent's training session, there was significant shock and surprise among many athletes and officials.

Just not at the U.S. Soccer Federation.

The episode in France -- which led to the team being penalized six points at these Games, as well as the head coach and two staffers being banned from soccer for a year -- is just the latest in a long pattern of similar circumstances involving Canadian teams attempting to view other teams' closed practices, multiple sources with connections to U.S. Soccer told ESPN. And there have been frequent instances when American teams were the targets.

Asked why U.S. Soccer never went to a governing body like CONCACAF or FIFA to investigate Canada Soccer, one source pointed to the larger relationship between the federations -- they worked for years to bid together, along with Mexico, for the 2026 World Cup, for example -- and the inevitable awkwardness such a claim would create.

"It wasn't worth it with so many bigger-ticket issues out there," the source said. "But that doesn't mean it didn't matter."

Among several specific instances in recent years that are often recounted among U.S. Soccer officials, sources told ESPN, is an incident during a training camp in January 2021. Both federation's men's teams were practicing in Florida at the IMG Academy, and on the day before the teams were set to stage a scrimmage against each other, the United States team was training at the facility's soccer stadium.

During training, a team security guard noticed a man sitting in the otherwise-empty adjacent football stadium watching the U.S. practice. The security guard approached the man and asked him who he was. The man said he worked for IMG Academy, at which point the security guard told him that he wasn't allowed to be watching practice. The man said he would leave, and the security guard went back to training. Moments later, the security guard looked back, and the man had simply moved to a different point in the football stadium to continue watching.

At that point, the security guard asked another IMG staff member who the man was, and was told, "He doesn't work for us." The security guard then returned to the football stadium and confronted the man, who finally admitted he was a Canada staffer.

The episode may have been a preview, of sorts; later that year, Canada's women's team won the gold medal at the Tokyo Olympics -- when it now appears they used drones to view opponents' practices, according to David Shoemaker, the Canada Olympic Committee's chief executive.

"It makes me ill, it makes me sick to my stomach, to think that there could be something that calls into question ... one of my favorite Olympic moments in history," Shoemaker said at a news conference this week.

When asked to comment on the latest allegations, a Canada Soccer spokesman pointed ESPN toward Shoemaker's news conference and the federation's previous statements, including one announcing a full independent investigation.

Multiple U.S. Soccer sources told ESPN that they believe any investigation will find that John Herdman, who coached Canada's women's team from 2011 to 2018 and its men's team from 2018 to 2023, was a common denominator.

Herdman on Friday denied any involvement in the practice of trying to watch other teams' closed trainings, saying that his thoughts were with the players and that he would assist Canada Soccer in the investigation. But the list of instances when Canada's soccer teams are alleged to have attempted to watch closed practices is extensive.

In addition to the 2021 episode, there was also an incident in 2019, before Canada and the U.S. played in the men's Nations League. On that occasion, U.S. Soccer staffers saw a drone attempting to film their practice session the day before the game.

According to TSN, the men's team also flew a drone over Honduras' training session before a match two years later. Demonstrating just how systemic the practice became, Canada Soccer also acknowledged in its news conference that the men's team attempted to utilize drones to view training sessions during this past summer's Copa América, when it reached the semifinals.

Canada Soccer CEO Kevin Blue said it was his understanding that it did not have an impact on the competitive integrity of the match at the Copa América but would not offer details.

In an odd twist, U.S. Soccer officials often joked with each other about Herdman's penchant for publicly suggesting that Canada was actually nervous that other teams were spying on them, and that position -- that Canada was the one at risk of being targeted -- seeped into other Canada Soccer staffers, sources said.

For example, two sources recalled an incident in 2017, when the U.S. women's team faced Canada's women's team in a friendly at Avaya Stadium in San Jose, California. At that stadium, there is a training field alongside the main stadium, and before Canada's day-before-the-game practice, a Canada Soccer official approached U.S. Soccer officials and accused the U.S. of installing cameras on the roof of the adjacent stadium, pointing at a pair of objects on the roof over and over.

When baffled officials went up to the roof to look at the objects, they found only a pair of plastic birds -- designed to keep actual birds from sitting on the roof -- as well as two pigeons.

There was also an incident, more recently, when Herdman was leading the men's team, and he complained about a drone flying over Canada's practice ahead of a Gold Cup match. After an investigation, it was discovered that the drone was only there during the open period of practice and that it was being flown by the host broadcaster for the tournament, who was simply capturing beauty shots for use at the start of the telecast.

"With Herdman and Canada," one official said, "it was always just a little, 'He doth protest too much.'"

Bev Priestman, the current Canada women's team head coach who is now suspended, was an assistant under Herdman before taking over in 2020. She was in charge of the women's team when they won gold in Tokyo -- an accomplishment that is now being viewed through a very different lens.

While day-before-match training sessions in other sports are often glorified walk-throughs, in international soccer -- where players are not together all the time the way they would be on a club team -- the sessions can be quite valuable, sources told ESPN.

Teams will frequently go over how they plan to press their opponent or what side they will try to shade possession toward. There are also run-throughs of free kick setups and rehearsals of any trick plays that might be called, as well practicing for penalty kicks. The starting lineup is also visible, which can be useful for an opponent in situations when a player might be injured or a question might exist over what player a team might use in a certain position.

"Being able to see those sessions doesn't give you everything," a U.S. Soccer official said. "But it can absolutely give you a lot."

Information from ESPN's Jeff Kassouf contributed to this report.