The Iran-backed Houthis vowed to lead a strong retaliatory response if the U.S. military strikes Yemen after President Donald Trump condemned the armed rebel group’s recent attacks against Saudi Arabia.

“If the U.S. becomes involved in the aggression against Yemen, we will not deliberate over the decision to respond,” Houthi political bureau member Mohammed Al Bukhaiti said on Monday, per Agence France-Presse. “Rather, there will be a swift and painful response targeting the U.S. and all its interests in the region.”