Hackers backing Tehran say an uncertain ceasefire between Iran and the United States and Israel won’t end their retaliatory cyberattacks, a warning that American cybersecurity experts say potential targets in the U.S. and Israel should take seriously.

One leading hacking group known as Handala said after the ceasefire announcement that it was temporarily postponing attacks on the U.S. but would continue to target Israel. It vowed to revive its efforts against America when the time was right — demonstrating again how digital warfare has become ingrained in military conflict. Already, the two-week ceasefire appears at risk of fraying over significant disagreements between the parties, which each are claiming victory in the war.