U.S. President Donald Trump elicited surprise, as well as a rebuke from HBO, after tweeting a picture of himself with the words "Sanctions Are Coming November 5."

The tweet, which echoes the popularly-quoted tag line "Winter is Coming" from HBO’s hit fantasy TV series Game of Thrones, uses similar-looking branding to Game of Thrones. HBO, owned by AT&T, responded in kind a few hours later with this tweet:

The network also told CNBC: “We were not aware of this messaging and would prefer our trademark not be misappropriated for political purposes.”

Dothraki is a fictional language spoken by the Dothraki people in George R. R. Martin’s Game of Thrones novels and the HBO adaptation.

Nov. 5 is the date when sanctions against Iran will come back into effect after Trump’s decision in May to walk away from a deal which had previously suspended them. The president, who has not previously expressed a particular preference for Game of Thrones, tweeted ahead of next week’s Nov. 6 midterm elections.