With Iran’s short lived rapprochement with the Western bloc, which began following the signing of the JCPOA nuclear deal in 2015, apparently at an end following both the United States’ unilateral withdrawal from the agreement and European threats to impose economic sanctions on Tehran over its ballistic missile program, the country is likely to rely more heavily on and seek to further improve relations with more reliable and older partners including China, the Koreas and Russia. As China in particular holds promise for investment in Iran, as well as potentially providing the country with the means to modernise its military, an understanding of the history of Beijing’s defence ties with Tehran assistance for its nuclear program provides invaluable context for relations today. While the Western aligned Shah of Iran had for decades been a close Western client, the United States’ primary ally in the Middle East providing the U.S. with invaluable military bases bordering the Soviet Union, the overthrow of the Pahlavi dynasty in 1979 brought about a significant shift in Iranian foreign policy. Iran’s subsequent war with Iraq, an oil rich Arab state which enjoyed the support of the United States, the Soviet Union and France, forced Tehran to seek alternative sources of arms - with North Korea and China emerging as key suppliers. While North Korean artillery, ballistic missiles and rifles all entered Iranian service in considerable numbers, where they remain to this day, China also proved an invaluable supplier of arms for the newly formed Islamic Republic. As well as small arms, Beijing also provided Tehran with ballistic missiles to counter the Soviet made Scud B platforms operated by Iraq. Silkworm anti ship cruise missiles also proved an invaluable asset in Iranian hands, and were used to great effect in the Persian Gulf causing particular concern for the United States and Iraq. China has provided Iran with a number of weapons systems from Type 56 assault rifles to Type 021 and C 14 Class missile boats and Type 54 and WAC-21 Howitzers among several other weapons systems. Cooperation continued after the Iran-Iraq War ended, and&nbsp;China sold Iran two dozen modernised variants of its J-7 single engine fighters, much needed in light of the heavy losses the Iranian Air Force suffered during the eight year conflict, as well as reportedly later aiding Tehran in developing its indigenous Saeqeh light fighter - an advanced derivative of the U.S. F-5 Tiger. China has also reportedly aided Tehran in developing an indigenous derivative of the advanced U.S. RQ-170 stealth drone, with Iran allowing Chinese specialists to examine the drone to develop their own designs as well.&nbsp;China also played a key role, alongside North Korea, in helping Iran start its own military industrial sector. A number of Iranian missile platforms are based heavily on Chinese technologies, including the Oghab and Nazeit missiles and Nasr anti ship cruise missile, a direct derivative appearing nearly identical to the Chinese C-704. Most Iranian anti&nbsp;ship&nbsp;missile types in service today are domestic variants of Chinese designs built as almost identical copies.&nbsp;Other platforms such as the Shahab 3 and Khorramshahr are based on North Korean ballistic missiles&nbsp;such as the Rodong-1 and Musudan. China reportedly played a significant part in helping Iran establish production facilities for the Nasr anti ship missile in 2010, a&nbsp;platform&nbsp;designed to be launched by the&nbsp;country's&nbsp;F-4 heavy fighters&nbsp;which were key to deterring U.S. military action in the Persian Gulf and providing the country with a small maritime&nbsp;anti&nbsp;access area denial (A2AD) zone.Alongside conventional military support China has also provided critical assistance for the Iranian nuclear program, providing technical expertise and training Iranian nuclear engineers and specialists for uranium exploration and mining long before the signing of the JCPOA. From the mid 1980s China provided Iran with critical nuclear technologies and machinery and helped the country’s technicians master the use of lasers for uranium enrichment. Chinese engineers and technicians played a key role in helping establish the Esfahan Nuclear Research Centre, a facility which played a central role in the development of the Iranian nuclear program. With China providing Iran with significant assistance to weather the effects of Western sanctions, including use of barter agreements to avoid U.S. economic sanctions for dealing with Iranian banks, it has seriously undermined the Western pressure campaign against the country. Beijing has become perhaps Tehran’s most invaluable partner, able to provide arms, trade and purchase large quantities of Iranian oil while helping the country weather Western pressure. China is today Iran’s largest trading partner, and with the JCPOA prohibition on Iranian imports of offensive weapons ending in 2020 Tehran is likely to look to China to further modernise its armed forces. Rumours that Iran has show interest in acquiring large numbers of Chinese elite J-10 light fighters could well be substantiated after this date, while the heavier J-11 air superiority fighter and possibly even the Chengdu J-20 stealth fighter could well contend with Russian Sukhoi platforms for a place in the Iranian inventory - much needed to match the vast F-15 fleets of hostile Saudi Arabia and Israel. Ultimately the Western bloc’s pressure on and threats against Tehran are set to drive it to further strengthen its relations with its Asian partners, foremost of which is China which can provide the country with a combination of military and economic benefits in a way other powers such as Russia and the Koreas cannot match.