China and Russia are also free to accept or deny any order, and until now they refused to provide weapons bigger than small arms to Iran and the last delivery took 10 year to come to Iran (S-300pmu) and one Yak trainer after countless pressure from the US on RussiaIran was under military procurement sanctions - those sanctions are gone. Iran is free to do what it wants.
Iran needs a lottery ticket to buy from them while other countries such as Indonesia, Pakistan, India, Algeria, Egypt etc buys and gets delivered quick any weapon proposed for sale and even get factories and licenses to build them
90% of the Russian and Chinese catalogue is inaccessible for Iran (anything bigger than guns and ammunition)