The United States under Trump unilaterally tore up the Iranian nuclear agreement signed with Iran and restarted, a series of extreme sanctions against Iran, which forced Iran to take measures to fight back.
After restarting a large number of centrifuges, Iran now has the ability to refine enriched uranium with a richness of 20%. On the face of it, this figure is still no small distance from the 90% enriched uranium that can be used to make weapons. But in fact, between 20% and 90%, there are almost no technical barriers, coupled with the fact that Iran has mastered sufficient and mature ballistic missile technology in the past period of time, once Iran can develop nuclear weapons on its own, then there is no doubt that there is a big threat to the United States.

However, all this is also self-inflicted by the Americans, if it is not Trump's reckless behavior, then the relationship between the United States and Iran can be basically developed in accordance with the general tone set by the "Iranian Nuclear Agreement". It is also worth mentioning that the UN Security Council's arms embargo on Iran expired in October last year, and although the Americans want the international community to continue the embargo, Iran's allies and opponents of the United States will not recognize it at all.
Although the United Kingdom and other small countries, regardless of whether there is an arms embargo agreement, will not sell weapons to Iran, but Iran has Russia behind the support, the two sides have long carried out a lot of military cooperation. So far, the largest tonnage of the Iranian Navy's capital ships is the three Kilo-class conventional-powered submarines obtained in the 1990s.
According to the latest report of iran's Fars news agency, Mohammed Bagheri, chief of the general staff of the Iranian armed forces, said in an interview with the media a few days ago that he has reached a naval cooperation agreement with Russia and will expand cooperation between the two countries in naval weapons and equipment and joint military exercises in the future.
Bagheri recently led the Iranian delegation to visit St. Petersburg, the largest city in northern Russia, and held a meeting with Russian Defense Minister Shoigu, Chief of the General Staff Gerasimov, and Deputy Commander-in-Chief of the Navy, Kasatonov. Russia's move can be described as an open step, the first step of the international community to lift the arms embargo on Iran, and of course, it also personally punched the Americans in the face.
In fact, the military cooperation between Russia and Iran has a long history, but for a long time in the past, due to the international community's arms embargo on Iran, it was impossible to export weapons and equipment to Iran on a large scale. During the Abu Dhabi International Defense Exhibition IDIX-2021 in February this year, a representative of the Russian Federation's Military And Technical Cooperation Agency said in an interview with the media that Iran was interested in purchasing Russian weapons, and Russia was also very willing to sell them.
In the future, Iran will buy weapons and equipment from Russia, which may first be in the fields of air force equipment and anti-ship missiles. It should be known that the absolute main force in the Iranian Air Force is the American F-14A fighter that has joined the Service of the Iranian Air Force in the late 1970s, and this fighter is also the product of cooperation with the Americans during the Pahlavi dynasty in Iran. In addition, Iran from the American F-5 series of fighters, reverse engineering from the "Lightning 80" "Kausal" and so on, Iran in the past few years, launched a so-called "stealth fighter" Conqueror 313, in fact, is the level of model aircraft.
Previously, it has been reported that Iran is very interested in the Russian Su-30SM fighter, and if they reach a purchase agreement with Russia, it will undoubtedly greatly enhance the combat effectiveness of the Iranian Air Force. Su-30SM is a heavy-duty multi-role fighter, and its downgraded export models also include India's Su-30MKI fighter, the series of products is very mature and reliable, and the related supporting system is also highly stable. And Russia's latest, KH-47M2 "Dagger" hypersonic missile, can also be equipped on heavy fighters. This kind of missile has also become an important supporting equipment for Russia's export heavy fighters! In this way, if Iran buys a fighter, it can basically have Russian-made hypersonic missiles immediately!