JERUSALEM (AP) — Israel’s national cyber chief Thursday officially acknowledged the country had thwarted a major cyber attack last month against its water systems, an assault widely attributed to arch-enemy Iran, calling it a “synchronized and organized attack” aimed at disrupting key national infrastructure.

Yigal Unna did not mention Iran directly, nor did he comment on the alleged Israeli retaliation two weeks later said to have shut down a key Iranian port, but he said recent developments have ushered in a new era of covert warfare, ominously warning that “cyber winter is coming.”

“Rapid is not something that describes enough how fast and how crazy and hectic things are moving forward in cyberspace and I think we will remember this last month and May 2020 as a changing point in the history of modern cyber warfare,” he said in a video address to CyberechLive Asia, a digital international cyber conference.

“If the bad guys had succeeded in their plot we would now be facing, in the middle of the Corona crisis, very big damage to the civilian population and a lack of water and even worse than that,” he added.

Israel and Iran are bitter foes who have engaged in years of covert battles that have included high-tech hacking and cyber attacks. Most famously, U.S. and Israeli intelligence agencies are suspected of unleashing a computer worm called Stuxnet years ago in an attempt to disrupt Iran’s nuclear program.

But Unna said the attempted hacking into Israel’s water systems marked the first time in modern history that “we can see something like this aiming to cause damage to real life and not to IT or data.”