Khamenei's warning comes after the US conducted airstrikes against Iran's Fordow nuclear site, using 30,000-pound bunker-buster bombs that caused visible damage even from space.

The fight between two well-armed Mideast powers has their neighbors worried about the conflict spreading, a concern only deepened by U.S. involvement.

“If the Middle East is unstable, the world will not be at peace,” Chinese President Xi Jinping said Thursday. “If the conflict escalates further, not only will the conflicting parties suffer greater losses, but regional countries will also suffer greatly.”