In recent weeks, a cyberattack on Iran’s nationwide fuel distribution system paralyzed the country’s 4,300 gas stations, which took 12 days to have service fully restored.

That attack was attributed to Israel by two U.S. defense officials, who spoke on the condition of anonymity to discuss confidential intelligence assessments. It was followed days later by cyberattacks in Israel against a major medical facility and a popular L.G.B.T.Q. dating site, attacks Israeli officials have attributed to Iran.

The escalation comes as American authorities have warned of Iranian attempts to hack the computer networks of hospitals and other critical infrastructure in the United States. As hopes fade for a diplomatic resurrection of the Iranian nuclear agreement, such attacks are only likely to proliferate.

Hacks have been seeping into civilian arenas for months. Iran’s national railroad was attacked in July, but that relatively unsophisticated hack may not have been Israeli. And Iran is accused of making a failed attack on Israel’s water system last year.