An unauthorized leak of classified documents suggests Israel is staging military exercises in the wake of a major missile attack on Iran at a time when tensions between the two countries are at their peak.

The United States is reportedly investigating the leaked information, which has been marked top secret. Documents show Israel undergoing military exercises following Iran’s fierce missile attack on October 1.

The documents, which can be shared within the Five Eyes intelligence alliance, which includes the US, UK, Canada, New Zealand and Australia, were published on pro-Iran Telegram channels on Friday. According to The Times, they are attributed to the US National Geospatial-Intelligence Agency and the National Security Agency (NSA).

It turned out that both documents were based on satellite information obtained between October 15 and 16.

The first one is titled: “Israel: Air Force continues preparations for attack on Iran and conducts second large force exercises,” reports the Reuters news agency.

The second is titled: “Israel: Defense Forces Continue Preparing Key Munitions and Covert UAV Actions Almost Certainly to Strike Iran.”

The military exercises appear to be reminiscent of attacks carried out by Israel last month on Houthi rebels and involved at least 16 airborne missiles, 40 state-of-the-art “Rocks” missiles and tankers.

On October 1, Iran fired nearly 200 ballistic missiles at Israel, a small number of which hit the central and southern parts of the country, with most being intercepted. It was Iran’s second such attack on Israel this year, after launching around 300 missiles and drones in April.

The leak does not indicate exactly which targets may be in Iran and whether they are standard military targets or sites linked to its nuclear program or oil industry.

US President Joe Biden has urged Israeli Prime Minister Benjamin Netanyahu to avoid striking both countries because crossing Iran’s “red lines” could trigger a wider regional war.

The documents also do not reveal any secret activity that Netanyahu might be planning. The US agencies involved, as well as the Israeli government, have not commented publicly on the leak.

However, Mike Johsnon, Speaker of the US House of Representatives, told CNN on Sunday that “the leak is very disturbing.”

He said: “Some serious allegations have been made, an investigation is ongoing and I will have an update on this in a few hours.”