This is not always a matter of not being united - it can be the sheer difference in power. When Donald Trump decided to punish Iran he forced EU companies to r

This is not always a matter of not being united - it can be the sheer difference in power. When Donald Trump decided to punish Iran he forced EU companies to retract from Iran as well (despite having contracts there). If we were to not comply, there would be sanctions against EU companies operating in the US. We asked the EU Commission for help on that but ultimately the EU did not have enough weight. So we got off Iran. Note that I am not addressing the human/ethical aspects of operating in Iran, just the economic imbalance between the US and EU