Hamas operatives used phone lines installed in tunnels under Gaza to plan Israel attack over 2 years, sources familiar with intelligence say

Intelligence shared with the United States suggests a small cell of Hamas operatives planning the deadly surprise attack on Israel communicated via a network of hardwired phones built into the network of tunnels underneath Gaza over a period of two years, according to two sources familiar with the matter.

The phone lines in the tunnels allowed the operatives to communicate with one another in secret and meant they could not be tracked by Israeli intelligence officials, the sources told CNN.

During the two years of planning, the small cell operating in the tunnels used the hardwired phone lines to communicate and plan the operation but stayed dark until it was time to activate and call on hundreds of Hamas fighters to launch the October 7 attack, the sources said.

They avoided using computers or cell phones during the two-year period to evade detection by Israeli or US intelligence, the sources said.

"There wasn't a lot of discussion and back and forth and coordination outside of the immediate area," one of the sources said.

The intelligence shared with US officials by Israel reveals how Hamas hid the planning of the operation through old-fashioned counterintelligence measures such as conducting planning meetings in person and staying off digital communications whose signals the Israelis can track in favor of the hardwired phones in the tunnels. It offers new insight into why Israel and the US were caught so flat-footed by the Hamas attack, which saw at least 1,500 fighters pouring across the border into Israel in an operation that killed at least 1,400 Israelis.

CNN has not seen the specific intelligence but spoke to sources familiar with it. The US Office of the Director of National Intelligence declined to comment and the Israeli embassy in Washington did not respond to a request for comment.