Image copyright Getty Images

America does not even like football, or so many people think. Why is it leading the charge against alleged Fifa corruption?

At dawn, Swiss police rounded up seven Fifa officials at the behest of US authorities who have conducted a massive investigation into corruption at football's governing body.

So how did a country where football is more niche than entrenched come to police the world's beautiful game?

"Too many countries are cowed by Fifa," said Alexandra Wrage, a former Fifa anti-bribery adviser who resigned in protest from the organisation.

"As with international bribery more generally, the US Department of Justice has said they'll step up to investigate corruption if others won't," she said.

How can the US police a global game?

Image copyright AP Image caption The suspects were shielded from journalists by a white sheet

Speaking to reporters just hours after the arrests in Switzerland, FBI Director James Comey set out why the US was able to act.

"If you touch our shores with your corrupt enterprise, whether that is through meetings or through using our world class financial system, you will be held accountable for that corruption," he said.

As it turns out, the US charges accuse many of those football officials of doing both.

To prosecute cases that involve foreign nationals, US authorities need only prove a minor connection to the United States.

But in the case of the charges made public on Wednesday, the alleged corruption hit right at the heart of the game in the US.

Image copyright Reuters Image caption FBI Director James Comey

Fifa and the confederations under it make money by selling the marketing and media rights to the World Cup and other tournaments that they organise.

The charges largely relate to "the systematic payment of bribes and kickbacks" that were paid by marketing executives who wanted to increase their chances at winning contracts for the rights to market and sell media access to tournaments.

These bribes were at times organised during meetings in the US, and some of the money was transferred through US bank accounts.

What sparked the US investigation?

At a news conference on Wednesday, the acting US Attorney for the Eastern District of New York, Kelly Currie, noted the scale of the allegations.

"This sort of bribery and corruption in international soccer has been going on for two decades. Our investigation...that itself took years," he said.

Image copyright AP Image caption Fifa President Sepp Blatter (r) with Mohammed bin Hammam in Qatar in 2010

It is not clear what specific event - if any - prompted the US investigation. Some have pointed to the United States' failed bid in late 2010 to host the the 2022 World Cup, and suspicions that bribes were paid to encourage votes for Qatar.

"I know some people who were in the US bidding committee... They all had really strong suspicions that somebody was getting bought off," said Andrew Zimbalist, author of Circus Maximus: The Economic Gamble Behind Hosting the Olympics and the World Cup. He told the BBC that he suspected the justice department probably got involved following the failed bid.

The choice of Qatar raised suspicions in part because of the extremely high temperatures it experiences during the summer months - a fact that prompted a Fifa taskforce to recommend the games be played in November and December rather than the usual June-July timeframe.

In the hours after the dawn arrests, Swiss authorities said they were opening a separate investigation relating to the bids for the 2018 and 2022 World Cup tournaments.

How deep are the US ties to the case?

The Miami offices of Concacaf, the football federation under Fifa that governs the game in North and Central America and the Caribbean, were raided by FBI agents early on Wednesday.

Two of the people who have been charged - Jeffrey Webb and Jack Warner - are the current and past heads of Concacaf, respectively.

Image copyright Getty Images Image caption Authorities raided Concacaf headquarters in Miami early on Wednesday

It is not clear what specifically the authorities are looking for in these raids, but many of the charges that were revealed today involve bribery and kickback schemes.

These schemes are related to the media and marketing rights for World Cup qualifying games in the Concacaf region, as well as the Concacaf Gold Cup, the Concacaf Champions League, and several others.

At the centre of some of these schemes was Traffic Sports USA, a sports marketing firm with ties to Brazil, and its owner Aaron Davidson. In another part of Miami, the FBI on Wednesday picked up Aaron Davidson , the president of Traffic Sports USA, who the Justice Department implicated in some of the bribery scandals.

The Copa America, which is set to be held for the first time outside of South America in 2016 when it will be played in the US, was highlighted for the corruption that surrounds it.

"Our investigation revealed that what should have been an expression of international sportsmanship was used as a vehicle in this broader scheme to line executives' pockets with bribes totalling $110 million [£71m], nearly a third of the legitimate cost of the rights to the tournaments involved," US Attorney General Lynch said during a news conference detailing the charges.

Concacaf has been in trouble in the past.

In 2012 Concacaf turned itself in to US tax authorities and admitted to not paying taxes for several years.

Image copyright EPA Image caption Chuck Blazer's plea was unsealed on Wednesday

Among those at the helm of the organisation was secretary general Chuck Blazer, who also served as a Fifa executive committee member.

It was also revealed on Wednesday that in 2013 he pleaded guilty to several charges related to corruption.

Just months ago, the New York Daily News reported that Mr Blazer has been working as an informant for US authorities.

The newspaper said that he met with football officials on the sidelines of the 2012 Olympics in London, and used a hidden microphone on a keychain to gather intelligence.

This report has not been independently confirmed. Officials say the corruption investigation is on-going.

"Nobody is above or beyond the law," FBI Director Comey said. "We will not stop until we send messages that this is not the way things should be and that they must be different".