The massive strikes conducted by the U.S. and Israel on Saturday — dubbed “Operation Epic Fury” by American forces — have been in the works over the past several “months leading up to the attack,” according to Israel officials.

In the first IDF statement following the attack on Iran, an Israel Defense Forces spokesperson said that “the strike included an attack on dozens of military targets.”

The statement also highlighted what appears to be the IDF’s close cooperation with United States across months of planning. The United States has not yet mentioned anything about the planning of the operation or how long it has been in the works for.

“In the months leading up to the attack, close joint planning was carried out between the IDF and the U.S. Army, which enabled the broad attack to be carried out with maximum synchronization and coordination between the armies,” the IDF said.

“The Iranian regime has not abandoned its plan to destroy Israel,” the statement continued. “The IDF has recognized that the regime has continued its attempts to fortify, protect, and conceal its nuclear programs, along with restoring the missile production process.

“The regime has continued to finance, train, and arm its proxies based within the borders of the State of Israel,” the IDF said. “These are actions that constitute an existential threat to the State of Israel, and threaten the Middle East and the entire world.”

The strikes involved a mix of U.S. aircraft and Tomahawk cruise missiles fired by U.S. Navy ships in the region, according to a U.S. official.

There are currently an estimated 35,000 U.S. military personnel stationed in the Middle East at the moment.

The U.S. already has large military bases in the region, with Al Udeid in Qatar being the largest with around 10,000 personnel. Close by in Bahrain, there are about 3,200 personnel and dependents stationed at the Navy’s Fifth Fleet headquarters.

There are also an estimated 1,000 U.S. troops in Syria, even as they prepare to draw down and leave the country, as well as another 2,500 troops in Iraq now mostly located in Erbil to the north.

The U.S. also has dozens more fighter jets in the Middle East than there were in mid-January.

An aircraft carrier — the USS Gerald R. Ford — along with up to four destroyers may soon join the 12 Navy ships already in the region, that includes the USS Abraham Lincoln.

In response, Iran immediately accused the U.S. of violating “all international laws and during negotiations.”

“Now is the time to defend the homeland and confront the enemy’s military aggression,” a statement released from the Iranian Ministry of Foreign Affairs said on Saturday. “Just as we were ready for negotiations, we have been more prepared than ever for defense. The armed forces of the Islamic Republic of Iran will respond to the aggressors with authority.”

ABC News’ Luis Martinez and Jack Moore contributed to this report.