Iran is seeking the S-400 air defense system from Russia, Bloomberg News reported on March 2, citing Israeli and American sources.

The sources said that the possible acquisition of the sophisticated air defense system by Tehran would speed up an Israeli decision on a possible attack on Iranian nuclear sites. Russia has not yet said publicly whether it will supply the system.

The S-400 air defense system was developed by Russia’s defense giant Almaz-Antey to counter all sorts of airborne threats, including stealth fighter jets, cruise missiles, drones and ballistic missiles.

The system utilizes several types of missiles with different specifications, with the most capable being the 48N6 and 40N6E with the ranges of 250 and 400 kilometers respectively. The main radar of the system, the 91N6, has a maximum detection range of up to 600 kilometers.

According to Bloomberg News report, Iran could need up to two years to operate the S-400 system if a deal was reached with Russia.

Russian-Iranian military cooperation grew last year. The United States and its allies claim that Russia received hundreds of combat and suicide drones from Iran for use in its special military operation in Ukraine.

In 2019 some Iranian officials expressed interest in procuring the S-400 missile system to further improve its defense capabilities along with the previously purchased S-300PMU2. Russia stated at the time it was ready to sell the S-400 system to Iran if an official request was made.

The reports of a possible S-400 deal came following talk of Russian preparations to deliver several weapon systems, including some two dozen Su-35 fighter jets, to Iran.

Israel has been threatening Iran over its nuclear program for the last two decades. Tensions rose after the U.S. withdrew from the 2015 nuclear deal. Talks to resolve the issue slowed down last year, which explains why Tehran may be preparing for a worst case scenario.