London (CNN) The ugly sound of monkey chants and the sinister sight of football fans performing Nazi salutes have been beamed around the world. Now all eyes turn to UEFA, European football's governing body.

UK Prime Minister Boris Johnson called the racist abuse England's black players suffered before and during the Euro 2020 qualifying match against Bulgaria in Sofia on Monday as "vile" and has told UEFA to act swiftly, to "face up to facts."

After a night English Football Association's chairman Greg Clarke described as "one of the most appalling I've seen in football," the pressing question now is: What punishment will Bulgaria face for some of its fans' abhorrent behavior?

The fallout has already begun. Bulgaria's Prime Minister called for the president of the country's football association to resign immediately. Borislav Mihaylov has since announced he will step down.

In addition, the country's interior ministry confirmed six people have been detained in connection with the racist abuse.

"Work is still ongoing to identify other participants in the incident," read a statement Wednesday.

But if football wants to eradicate the racism which is bringing shame on the sport, what UEFA does next will have the biggest impact on effecting change.

UEFA's disciplinary proceedings have begun, with the Bulgarian Football Union charged with racist behavior, including chants and Nazi salutes, and the disruption of a national anthem and displaying replays on a giant screen. The English FA faces sanctions too, over national anthem disruption and an insufficient number of traveling stewards.

World governing body FIFA has also asked UEFA to notify it of any punishment potentially handed down to the BFU. "This would allow any sanctions imposed to be extended worldwide," said a FIFA statement.

Bulgaria's match against England was twice stopped because of the racist abuse coming from the stands.

Should the match have been abandoned?

But UEFA has already been heavily criticized, for what happened at the Levski Stadium in Bulgaria's capital, and for perceived ineffectual responses to previous racist incidents.

Troy Townsend, a member of the anti-discrimination organization Kick It Out, has said UEFA should ban Bulgaria from Euro 2020. "It's the only way people will take note of what they are doing to our black players," he said.

Former Arsenal and England striker Ian Wright, working as a pundit for UK broadcaster ITV, said the scenes in Bulgaria was "showing up UEFA for what they are," while Kick It Out itself has said the governing body failed to correctly implement its three-step protocol during England's 6-0 victory.

The Euro qualifier was stopped twice with fans warned of the consequences of their continued racist behavior. England manager Gareth Southgate said his players wanted to carry on playing and admitted his team was in an "impossible situation."

"We gave two messages -- one that our football did the talking and two, we stopped the game twice," he told reporters. "Not one player wanted to stop, they were absolutely firm on that."

Gareth Southgate speaks with referee Vasil Levski during the UEFA Euro 2020 qualifier.

UEFA insists its three-step procedure must be followed in the event of racist chants from the stands. It was put to the test in Sofia.

The first step of that procedure is to bring the match to a halt and instruct the stadium authorities to call on spectators to stop the discriminatory behavior.

If that goes unheeded, another announcement is made and the match is suspended with players sent to their dressing rooms for a "specific period." Lastly, following consultation, the match will be abandoned "if the discriminatory behavior still does not cease or breaks out again."

Did the protocol fail? There are those, England's players and coaching staff included, who would argue that England's players did their talking on the pitch despite the toxic atmosphere in which they played.

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But Kick It Out has questioned why the players weren't sent to the dressing rooms during the second step of the protocol.

"TV footage also clearly shows that racist abuse continued in the second half, so it is unacceptable that step three was not enforced," the organization said in a statement.

Such is the sorry state of racism in football, the abuse England's black players suffered in Bulgaria had been anticipated.

Last week striker Tammy Abraham said he and his teammates had resolved to walk off the pitch if they were subjected to racist abuse in Bulgaria and had discussed defying UEFA protocols. There should only be one step, said the Chelsea striker, if there is racist chanting and that is to walk off.

If ahead of an international match players are conducting meetings in expectation of some members of the team being racially abused, is that in itself not a sign that the protocols and punishments already in place are not working?

After all, the Levski stadium was partially closed for the England game as punishment for the behavior of some of Bulgaria's fans in June matches against the Czech Republic and Kosovo. A partially closed stadium can still be a racist stadium.

UEFA President Aleksander Ceferin has defended his organization against the criticism it is facing over the handling of recent racist incidents.

"I know we are not going to win popularity contests," he said in a statement on Tuesday. "But some of the views expressed about UEFA's approach to fighting racism have been a long way off the mark. UEFA's sanctions are among the toughest in sport for clubs and associations whose supporters are racist at our matches."

"Boring," tweeted Townsend in response to the statement. Ceferin made reference to the 10-match ban from European football given to Kostiantyn Makhnovskyi -- goalkeeper of Latvian side FK Ventspils -- in August for "racist conduct" during a Europa League tie against Malta's Gzira United.

But UEFA's past punishments have raised eyebrows.

A cat enters the field of play during a UEFA Champions League tie between Besiktas and Bayern Munich.

In 2012, English club Manchester City was fined 30,000 euros ($33,106) for coming out of the second half of a game "up to 60 seconds later" than scheduled. A month earlier, Porto fans had been fined 20,000 euros ($22,071) for racially abusing then City striker Mario Balotelli.

No single UEFA fine has come close to matching the 100,000 euro ($110,355) penalty handed to Denmark striker Nicklas Bendtner for exposing sponsored underpants while celebrating a goal against Portugal at Euro 2012.

Indeed, to much derision, Turkish Super Lig side Besiktas was fined 34,000 euros ($37,520) for allowing a cat to enter the pitch during its Champions League encounter with Bayern Munich in March 2018, while in November of that year Greece was handed a partial stadium ban and the country's football federation fined 9,819 euros ($10,822) for the racist behavior of some fans in a 1-0 win over Estonia.

Fines are meted out, stadiums are closed, and yet racism in football continues, as it has done for decades.

Serbia's Red Star Belgrade was reportedly ordered to pay UEFA fines totaling 191,000 euros ($210,486) last season and, so far in this campaign, the club has received fines totaling 122,000 euros ($134,446) for failing to control its fans.

Yet, Red Star continues to compete in UEFA's Champions League, a competition which distributed a total of 2.04 billion euros ($2.25bn) to clubs competing in the competition in the 2018/19 season.

UEFA orders clubs and federations to display banners with the wording "#EqualGame" but what use is that if, as happened on Monday, fans hold aloft jumpers with "No Respect" and a fake UEFA logo emblazoned across it?

Under UEFA rules, a first offense for racist behavior and other discriminatory conduct and propaganda results in a partial stadium ban as a minimum penalty, which occurred on Monday.

A second offense leads to one match being played behind closed doors and a fine of 50,000 euros ($55,000). A third offense, says UEFA, is "punished with more than one match behind closed doors, a stadium closure, the forfeiting of a match, the deduction of points and/or disqualification from competition."

The statement issued by UEFA's president on Tuesday said "football family" must "wage war on the racists."

"Football associations themselves cannot solve this problem. Governments too need to do more in this area. Only by working together in the name of decency and honor will we make progress," said Ceferin.

UEFA's task is not an easy one. It cannot tackle racism on its own, but whatever punishment it decides to hand out to Bulgaria will speak louder than its words.