This post is in partnership with Time. The article below was originally published at Time.com.
By Sam Frizell, TIME
Dick Costolo, the CEO of Twitter, has a bone to pick with Iran: you can’t use Twitter (TWTR) there.
And on Thursday, Costolo tweeted at Iranian President Hassan Rouhani—currently in New York City for the United Nations General Assembly—with a Twitter burn for the ages:
With access to Twitter and Facebook (FB) officially banned in the Islamic Republic, Iranians have to find other ways to bypass the state’s Internet filtering system. That’s if they’re not the country’s president, who is a prolific tweeter and apparently has unfettered access to the social network. But Costolo’s tweet isn’t just a muted form of digital social activism; it’s a pragmatic defense of his company’s business interests in Iran.
Rouhani doesn’t appear to have responded yet to Costolo’s tweet, which may be because it’s just too hard to come back from a tweet like that.