The Washington Post writes about it.
NPP Start, a factory in Yekaterinburg, under U.S. sanctions for backing Russia's Ukraine war, produces key components for anti-aircraft systems, including the S-400 missile, deemed capable of countering stealth jets like those of Israel and the U.S. The Iranian delegation visited the enterprise on the last day of its tour of Russian arms plants in March last year.
A leaked document characterized the trip as a demonstration of the scientific and technical potential and production capabilities that Russia can offer Tehran, suggesting deepening ties between the two nations since Russia's invasion of Ukraine. This partnership could become a key factor amid possible Israeli strikes in response to the drones and missiles launched this weekend.
According to the article, in 2022, Iran's agreement to supply drones and missiles to aid Russia in Ukraine marked a significant turn in their relationship. This has led to promises of advanced fighter jets and air defense tech from Russia, strengthening Iran's defenses.
While the extent of these arms transfers remains undisclosed, Russian technology could significantly bolster Iran's ability to intercept aircraft and missiles.
Collaboration extends beyond weaponry to include drone co-production, anti-jamming technology sharing, and intelligence exchanges.
According to the article, intelligence officials described Russia as " advancing" secret agreements to supply Iran with Su-35s, one of Russia's most powerful fighter-bombers and a potentially significant upgrade to Iran's air force, which is largely made up of converted U.S. and Soviet aircraft produced before 1979. Russia has also promised to provide technical assistance with Iranian spy satellites, as well as help in building rockets to put more satellites into space.
However, so far there is no public evidence that the Su-35s have been delivered. This may be due to Iran's delay in paying for the planes, according to a U.S. and Middle East intelligence official with detailed knowledge of the deal.
Russian agreements to supply Iran with antiaircraft missiles and anti-stealth systems could escalate tensions, potentially making Iranian airspace riskier for adversaries.
Despite uncertainties regarding the delivery of certain systems, Russia's assistance in improving Iranian military capabilities underscores a strategic partnership between the two countries.
The joint production of drones indicates Iran's gains in refining its military technology, benefiting from Russia's expertise and design improvements.
Even without overt arms sales, the exchange of knowledge between Russia and Iran could quietly strengthen Iran's defenses without drawing Western attention.
In essence, the evolving partnership between Russia and Iran presents a new challenge for regional security dynamics, particularly concerning Israel's military calculations.