Tehran, Iran – Ukraine’s Western allies claim Iran has sent short-range ballistic missiles to Russia in a major escalation – a claim Tehran has rejected as “completely baseless and false” and pointed to what it sees as Western hypocrisy.

The United States, Britain, France and Germany on Tuesday imposed more sanctions on Iran for what they called Tehran’s “escalatory” decision. They provided no evidence and the weapon has not been observed in the battlefield yet.

Tehran has described the latest sanctions on Iranian firms and individuals as “economic terrorism”.

The Kremlin, however, has not refuted the reports, instead branding Iran an “important partner”.

What’s the significance of the missiles?

The Western allies have accused Iran of giving Russia some 200 ballistic missiles of the Fath-360 model potentially slated to be used in Ukraine within weeks. Russia has been fighting a war with Ukraine, which has been backed by the West, since 2022.

The satellite-guided projectile, also known as BM-120, is a single stage, surface-to-surface, solid propellant ballistic missile that can be launched from up to six-round canisters mounted on the back of trucks.

The range is only up to 120km (75 miles) and it can carry an explosive payload weighing up to 150kg (330lb), with maximum speeds reaching Mach 4 – four times the speed of sound, or about 4,900 kilometres per hour (3,050mph). The missile is believed to have an accuracy of below 30 metres (98 feet).

The weapon by itself is unlikely to turn the tide of any war, but could potentially help Russia better manage its offensive on Ukrainian soil. The Fath-360 has often been compared with the US-made HIMARS systems that Ukraine has been using against Russian forces.

As the US has also pointed out, the Iranian missiles could be deployed to hit targets nearer to the front lines, allowing Russia to reserve its own precision-guided munitions for targets deeper inside Ukrainian borders.

Since shortly after the start of the war in 2022, Iran has also been accused of sending explosives-laden drones to Russia and helping train Russian forces and set up a drone production line, with Ukraine displaying parts of destroyed drones in battlefields as proof.

For its part, Iran has said it sold drones to Russia – but this happened “months” before the start of the war. It has also emphatically denied sending the missiles on multiple occasions since the claim was first made by Western officials in late 2022, with the foreign ministry on Wednesday promising to respond to the sanctions.

Would sending the missiles violate Iran’s nuclear deal?

The nuclear deal that Iran signed with world powers in 2015 to get relief from United Nations sanctions in exchange for limiting its nuclear programme also included provisions on missiles.

As part of the accord’s sunset clauses, a longstanding conventional arms embargo imposed on Iran expired in October 2020. More restrictions on Iran’s missile programme expired in October 2023, but the US and European Union kept their own sanctions to pressure the Iranian arms industry.

Technically, there are no international legal hurdles stopping Iran from sending the ballistic missiles.

But United Nations Security Council Resolution 2231, which underpins the nuclear accord, used the Missile Technology Control Regime (MTCR) that was formed by the G7 to define the prohibitions imposed on Iran as part of the arms embargo. Russia and China are MTCR partners, but the regime does not impose legally binding obligations.

The MTCR Category I stipulates that adhering states should not export missiles and drones with a range of more than 300km (186 miles) and a payload greater than 500kg (1,100lb).

The Fath-360 falls comfortably within the confines of Category I, which could mean that – if the allegations are true – Iran is treading carefully by not sending longer-range missiles. Earlier reports had speculated Tehran could be sending ballistic missile variants with ranges of up to 700km (435 miles) that could travel far beyond Ukraine.

Limiting the range of the exported missiles could shield Iran against the nuclear deal’s “snapback” mechanism that could reinstate all UNSC sanctions on Iran. If longer-range missiles were to be exported, the E3 could argue Iran was violating Category I Resolution 2231, which expires in October 2025.

Would missile exports to Russia make strategic sense for Iran?

Iran’s President Masoud Pezeshkian and his cabinet have come to power with support from Supreme Leader Ayatollah Ali Khamenei while emphasising they want more diplomatic engagement with the West and negotiations to lift sanctions.

Russia has also stirred the pot in Iran by supporting Azerbaijan’s Turkey-backed plan to establish the controversial Zangezur Corridor, linking mainland Azerbaijan to Nakhchivan through Armenia and cutting off a vital export line to Europe for Iran.

For these two reasons, a decision by Iran to send missiles to Russia would not appear to make strategic sense, according to Hamidreza Azizi, and visiting fellow at the German Institute for International and Security Affairs (SWP).

But beyond the timing, the Iran expert told Al Jazeera that Tehran could be expecting to finally take delivery of the advanced Russian Su-35 fighter jets that it has said it wants to procure, while looking to other military technology and joint weapons production with Russia.

“Furthermore, Iran and Russia have been cooperating in other strategic areas, such as space and nuclear programmes. Iran may also seek to deepen collaboration in these areas. So, while the timing might be questionable, these broader factors could be driving Iran’s incentives to proceed with the missile deliveries,” Azizi said.

What do we know about the latest Western sanctions on Iran?

In response to what they called a “dramatic escalation”, the US and E3 have further piled on sanctions on Iranian civil aviation, blacklisting flagship airliner Iran Air and cutting off its access to Europe.

Citing a “direct threat to European security”, the E3 said they would pursue designating entities and individuals involved with Iranian weapons programmes.

The US and United Kingdom blacklisted three senior military commanders who have been allegedly involved in exporting arms to Russia, along with four Iranian entities including the organisation running the Anzali Free Trade Zone in northern Iran. Five Russian ships and three aviation units were designated as well.

Did the US withdrawal from the nuclear deal get us here?

The landmark 2015 Iranian nuclear accord has been in limbo for years because Washington unilaterally abandoned it in 2018 and imposed the harshest-ever sanctions on Iran that remain in place today.

But the move, and the “maximum pressure” policy of the administration of former President Donald Trump that his predecessor Joe Biden has mostly continued, prompted Iran to increasingly veer towards Russia and China.

Iran and Russia have been cooperating in Syria as well, working for more than a decade to keep the government of President Bashar al-Assad in power.

Iran and China signed a 25-year cooperation agreement in 2021, but no major deals have been announced as part of the agreement. China, however, continues to be the largest buyer of Iranian crude oil despite the sanctions.

On the other hand, the Russian invasion of Ukraine led Moscow to seek new partners.

The US pressure on Iran has been a “major factor” driving further cooperation with Russia, and abandoning the nuclear deal was a “key moment” that pushed Iran to pursue a “look to the East” policy, Azizi said.

The expert said Iran and Russia share a desire to challenge US influence and hegemony globally, but this does not equal a formal military or economic alliance, even though there have been agreements.

“There’s no mutual defence pact or binding agreement that would, for example, commit Russia to defend Iran in a conflict, nor are there concrete agreements in other strategic areas,” he said.

“The strategic partnership agreement, which is reportedly in its final stages, is expected to focus more on generalities rather than specific mutual commitments. While their growing cooperation undoubtedly presents challenges for the US and Europe, it’s important not to overstate the relationship as a formal alliance. Still, both countries seem eager to continue expanding their cooperation.”