Russian military spies hacked hundreds of computers at the 2018 Olympic Games in South Korea — and tried to make it look like North Korea was the culprit, according to a new report. It is likely retaliation against the International Olympic Committee (IOC) for banning Russia from the Olympics because of a widespread doping scheme it used to cheat in previous competitions.

The Washington Post’s Ellen Nakashima reported on Saturday evening that the GRU, Russia’s military intelligence agency, accessed as many as 300 Olympics-related computers earlier this month, according to two US officials. To cover their tracks, and to pin any suspicions on North Korea, the hackers used North Korean IP addresses, among other tactics.

Officials in Pyeongchang had already acknowledged that the Winter Games were hit by a cyberattack during the February 9 opening ceremonies but hadn’t said who did it. That night, there were disruptions on the internet, broadcast systems, and the Olympics websites. Per the Post, many attendees weren’t able to print their tickets for the event, which left seats empty.

The GRU accessed South Korean routers in January and sent out new malware on the day the Olympics started, which might have allowed them to collect intelligence or attack networks. Soon after the Games began this month, a Russian cyber-spying group linked to the GRU, “Fancy Bear,” released a set of stolen emails purportedly belonging to international sports officials. The same hackers did something similar in the 2016 Summer Games in Rio de Janeiro, when they released the drug testing files for multiple athletes, including tennis player Serena Williams and gymnast Simone Biles.

Among US officials, there’s concern that the GRU might attempt to hack the Pyeongchang closing ceremonies on Sunday. One told the post that they are “watching it pretty closely” but that it is “essentially a Korean problem.” The official said the US will help out as requested.

The IOC could decide to reinstate Russia as soon as next week, but the country isn’t exactly helping its case

The IOC in December announced it was banning Russia from competing in Pyeongchang as punishment for a widespread, government-run doping scheme that allowed it to cheat in the 2014 Sochi Winter Olympics and the 2016 Rio de Janeiro Olympics.

It determined that some athletes from the country — 169 in total — would be able to take part in the Olympics, but under the designation “Olympic Athlete from Russia.” (If you’re confused on why you’ve been seeing OAR everywhere, that’s why.) The athletes were barred from wearing Russia’s colors and displaying the Russian flag, and if they won a gold medal, Russia’s anthem couldn’t be played. No officials from Russia’s Olympic federation were allowed to attend the Winter Games, and any medals won won’t go towards Russia’s medal count in the history books.

Russia hasn’t exactly behaved better this time around. Aside from the GRU’s hacking, a handful of Russian athletes have been caught doping in Pyeongchang, including bobsledder Nadezhda Sergeeva and curler Aleksandr Krushelnitckii. Krushelnitchkii and his partner, Anastasia Bryzgalova, had to forfeit the bronze medals they won at the Games.

The IOC on Sunday voted unanimously to uphold its suspension of Russia as a team from the Winter Olympics, meaning the country’s athletes won’t be able to march in the closing ceremony with their national colors or flag.

Nicole Hoevertsz, the leader of the IOC’s panel reviewing Russia’s compliance, told the New York Times that Russia could be reinstated within the next week — depending on the final doping test results, which are anticipated in the next few days.