JERUSALEM—In an unexpected act that Israeli president Shimon Peres called "thoughtful," al-Qaeda leader Osama bin Laden sent a belated threat to Israel Monday in honor of the Jewish state's 60th birthday. "Old fart!" read the front of the card in a font designed to look like ancient stone tablets. "Did you actually think I would forget my favorite infidels on their special day? Celebrate while you still can, dirty Zionist dogs!" bin Laden wrote under a caricature of a grinning al-Qaeda member wearing a birthday hat and a suicide belt, preparing to board a bus full of Israeli citizens. A visibly moved Peres told reporters he would return the gesture by sending a bouquet of a dozen F-15Is fighter jets to Lebanon next week.