Players from Russia and Belarus will not be allowed to compete at Wimbledon this year. The decision was announced Wednesday. The third Slam of the year became the first to ban players from those countries, in response to Russia’s invasion of Ukraine and Belarus’ close allyship to Russian president Vladimir Putin.

The All England Club (AELTC) — the Wimbledon organizers — said the decision was made to “limit Russia’s global influence through the strongest means possible.” The statement continued: “In the circumstances of such unjustified and unprecedented military aggression, it would be unacceptable for the Russian regime to derive any benefits from the involvement of Russian or Belarusian players with The Championships.”

The call means men’s world No. 2 Daniil Medvedev and women’s world No. 4 Aryna Sabalenka — who reached the semifinals last year at Wimbledon — are prohibited from playing. Here’s how Wimbledon came to this decision, and the ramifications of it.

Whom does this affect?

This has a huge impact on both the men’s and women’s singles draws at Wimbledon. On the men’s side, it prevents Australian Open finalist and No. 2 Medvedev from competing, as well as No. 8 Andrey Rublev, No. 24 Karen Khachanov and No. 30 Aslan Karatsev. The top-ranked Belarusian on the men’s side is No. 42 Ilya Ivashka.

On the women’s side, five of the top 40 are affected. World No. 15 Anastasia Pavlyuchenkova, Daria Kasatkina (No. 26) and Veronika Kudermetova (No. 29), all of Russia, will sit out this year’s competition. The decision also prevents Belarussian Aryna Sabalenka (No. 4) and former world No. 1 and current No. 18 Victoria Azarenka from competing.

How did Wimbledon get to this decision?

On March 1, the ATP and WTA tours and the International Tennis Federation (ITF) announced they would allow Russian and Belarusian players to continue competing in their tournaments, but without any reference to their nationality. Players such as Medvedev would compete, but would not have the country’s flag next to their name, nor would their country’s national anthem be played.

Russia and Belarus were banned from team events like the Davis Cup and the Billie Jean King Cup.

This stance has been the status quo across the Slams and tournaments. But the pressure in Britain from politicians has seen Wimbledon take a firmer stance. In early March, sports minister Nigel Huddleston suggested players should only be able to compete if they denounced Vladimir Putin.

“Absolutely nobody flying the flag for Russia should be allowed or enabled,” Huddleston said. “We need some potential assurance that they are not supporters of Putin and we are considering what requirements we may need to try to get some assurances along those lines.”

But there were concerns this stipulation would put the players and their families’ safety in danger.

Behind the scenes, discussions were ongoing. “We are in very close dialogue with the All England Club, the government, with the tours,” Lawn Tennis Association (the sport’s governing body in the U.K.) chief executive Steve Lloyd said earlier this month. “We are very conscious of public sentiment in this area. We are trying to navigate what that needs to look like in the summer events in Britain this year.”

The announcement Wednesday comes following lengthy discussions between the AELTC, the LTA and the government. The AELTC stated on April 5 the call over whether to allow Russians or Belarusians to compete was “a complex and challenging issue” and planned “to announce a decision in relation to Wimbledon ahead of our entry deadline in mid-May.”

News of the decision started to be reported on Tuesday evening, and by Wednesday morning, those reports had reached the Kremlin. “Given that Russia is a very strong tennis country, our tennis players are indeed at the top of the world rankings, the competition itself will suffer from their removal,” a Kremlin spokesman said Wednesday. “Once again, making athletes hostages of some political prejudices, political intrigues and hostile actions towards our country is not acceptable.”

Later on Wednesday, the AELTC confirmed the decision — and the decision to ban Russia and Belarus players from competing extended to all grass-court events this summer in the U.K. The statement said it was a decision made with “deep regret.”

“We recognize that this is hard on the individuals affected, and it is with sadness that they will suffer for the actions of the leaders of the Russian regime,” said Ian Hewitt, chairman of the All England Club.

The AELTC added that “if circumstances change materially between now and June, we will consider and respond accordingly.”

What are the ATP and WTA saying?

The ATP and WTA both issued statements Wednesday disagreeing with the announcement from the All England Club.

“We believe that today’s unilateral decision by Wimbledon and the LTA to exclude players from Russia and Belarus from this year’s British grass-court swing is unfair and has the potential to set a damaging precedent for the game,” said the ATP statement. “Discrimination based on nationality also constitutes a violation of our agreement with Wimbledon that states that player entry is based solely on ATP Rankings. … It is important to stress that players from Russia and Belarus will continue to be allowed to compete at ATP events under a neutral flag.”

The WTA said it was “disappointed in today’s announcement,” and went on to state, “A fundamental principle of the WTA is that individual athletes may participate in professional tennis events based on merit and without any form of discrimination. … As the WTA has consistently stated, individual athletes should not be penalized or prevented from competing due to where they are from, or the decisions made by the governments of their countries.

The statement concluded, “The WTA will be evaluating its next steps and what actions may be taken regarding these decisions.”

What about other tournaments?

Tournaments on the men’s and women’s side that were scheduled to take place in Moscow later this year were both canceled. The ITF has already suspended the Russian Tennis Federation and Belarusian Tennis Federation from its membership.

The next Slam up is the French Open, which starts May 22. Currently, it appears likely Russians and Belarusians will be permitted to compete at Roland Garros under the terms of national neutrality.

Amélie Oudéa-Castera, director general of the French Tennis Federation, said in mid-March: “At this stage, we do not intend to go into the details of personal and individual situations, which we also know can be extraordinarily dependent on the family situations experienced by each of them. In competition, individual athletes are only banned if they are selected by their countries to represent them. This is not the case in tennis; players are allowed to participate in tournaments on the basis of their ranking.”

To date, the US Open is adopting a similar stance.

What have the players said?

Rublev made international headlines when he wrote on a TV camera “no war please” at the Dubai Tennis Championships in February. In March, at Indian Wells in California, Medvedev said: “I don’t have any response to Wimbledon. Everybody knows what’s happening, so it’s basically of course impossible to ignore it [the invasion], but I always said everybody has different opinions on different things in the world. I always said I’m for peace. It’s very tough in life to talk what is fair and not fair. So I, of course, I do have my own opinions on different topics, but I prefer to speak about them with my family, with my wife, where we can sometimes disagree, but we can discuss.”

The ban has been supported by ex-player Olga Savchuk, who was captain of the Ukrainian team at the Billie Jean King Cup in their tie against the USA last week. “My strong position is, if there are sanctions, there have to be sanctions on everyone,” Savchuk said to Time. “Russia has to be isolated. Look at our kids and our families. People dying. Women and children. Russian tennis players at least have to feel uncomfortable.”

Marta Kostyuk, world No. 49, released a statement on Wednesday calling on the ATP/WTA and ITF to ask any Russian or Belarusian players to answer a series of questions about their support for Putin or Alexander Lukashenko’s regime in Belarus. Depending on the answer, she wrote: “If applicable, we demand to exclude and ban Russian and Belarusian athletes from competing in any international event, as Wimbledon [has] already done. There comes a time when silence is betrayal, and that time is now.”

Additional reporting by Kathleen McNamee.