Russia's links with Iran are growing stronger - and Ukraine and the West will have to retaliate
Western allies may retaliate with sanctions if Iran has provided Russia with ballistic weapons - and it could also convince them to relax restrictions preventing Ukraine from using long-range missiles inside Russia.
By Deborah Haynes, Security and Defence Editor @haynesdeborah
The head of the CIA has warned that any move by Iran to supply Russia with ballistic missiles for its war in Ukraine would be a "dramatic escalation" - but Ukrainian sources say this has already happened.