United States and British intelligence agencies have been hacking into and monitoring live feeds from Israel's drones and fighter jets for nearly 20 years, according information from documents leaked by former NSA contractor Edward Snowden and published Friday.

The National Security Agency and its British counterpart, GCHQ, gained a "virtual seat in the cockpit" of Israeli drones and other aircraft as they conducted military operations against Palestinians in Gaza, Syria, Lebanon and Iran, reported The Intercept.

The project, codenamed "Anarchist," operated since 1998 from a Royal Air Force installation situated near the highest point on the Mediterranean island of Cyprus.

"This access is indispensable for maintaining an understanding of Israeli military training and operations and thus an insight to possible future developments in the region," a classified GCHQ report from 2008 said, according to The Intercept.

That was the year Israel went to war against Hamas fighters in Gaza and began giving serious thought to attacking Iranian nuclear sites over fears that international diplomacy would fail to prevent the country from developing a nuclear bomb, notes Reuters.

Israel was the main focus of the operation, but it also targeted other Middle Eastern states, such as Egypt, Turkey, Iran and Syria. The drone feeds were reportedly decoded and accessed using the open-source program AntiSky, which is freely available on the Internet.

While there was no official comment from Israel, Energy Minister Yuval Steinitz, a member of Prime Minister Benjamin Netanyahu's security cabinet, said he was not surprised.

"We are not surprised; we know that the Americans spy on every country in the world and on us as well, on their friends. It is nevertheless disappointing because among other reasons, we haven't been spying or collecting intelligence or cracking codes in the United States for decades," he told Army Radio, according to The Associated Press. "I do not think that this is the deepest kingdom of secrets, but it is certainly something that should not happen, which is unpleasant. We will now have to look and consider changing the encryption, certainly."