Mark Zuckerberg told Facebook staff to block the Vine video app’s friend-finding feature, cutting off access the same day that the service launched. According to documents released today by the UK Parliament, Facebook executive Justin Osofsky proposed the move on January 24th, the same day the app appeared on iOS.

“Twitter launched Vine today, which lets you shoot multiple short video segments to make one single, 6-second video,” Osofsky wrote. “Unless anyone raises objections, we will shut down their friends API access today.”

“Yup, go for it,” replied Zuckerberg, according to the documents.

“Yup, go for it.”

Vine users quickly noticed that its friend-finding feature was broken, and they surmised that it was part of an ongoing feud between Facebook and Twitter, since Twitter had cut off its own friend-finding features for Facebook’s recently acquired Instagram app. Twitter eventually shut down Vine in late 2016, as its growth lagged behind alternatives like Snapchat.

Osofsky noted that Facebook had “prepared reactive PR” for its decision to block Vine’s API access. That may refer to a Facebook blog post called “Clarifying Our Platform Policies,” which Osofsky published on January 25th. That post didn’t mention Vine, but it called out a “much smaller number of apps that are using Facebook to either replicate our functionality or bootstrap their growth in a way that creates little value for people on Facebook,” compared to a larger pool of apps that “create personalized and social experiences, and easily share what they’re doing in your apps with people on Facebook.”

The exchange was part of a trove of documents released today by Parliament’s Digital, Culture, Media and Sport Committee. They were initially included in sealed court documents for an American lawsuit between Facebook and defunct app developer Six4Three, which created an app for finding bikini pictures on Facebook. The committee seized them last month over Facebook’s protests, but the contents were not initially made public. The exchange over Vine was included as an example of Facebook attacking competitors by denying them access to certain services, albeit in a way that was fairly well-documented at the time.