They were still not Iranian citizens and clearly, the seizure of British marines was an act of war. The Iranians like to seize hostages - so do most terrorists.
They claim dual citizenship. You decide what they are.
I shed no tears for them.
“Anyone carrying an Iranian passport is considered an Iranian citizen by the regime.”
Actually, that is partly correct.
Under Islamic Republic law the following applies:
1) Anyone born in Iran is considered an Iranian citizen. Especially so if he/she was issued an Iranian birth certificate or has previously held an Iranian passport or if his/her father is/was an Iranian by birth. Note: not mother, but father.
During Shah’s regime, a person whose mother only was Iranian could apply for an Iranian citizenship and be granted one, even if not born in Iran. But, IR does not allow it unless they can prove that they were in fact born in Iran, i.e. a birth certificate. However, I also hear that they are now re-considering the laws regarding the grant of Iranian citizenship if only one’s mother is Iranian by birth.
2) If one is born in Iran or has a father who is by birth an Iranian and has previously held an Iranian passport, he/she is considered an Iranian, under IR law, and regardless of dual citizenship and is subject to Islamic Republic laws when entering Iran.
Most governments advise and a few actually warn Iranians before their “naturalization” that if they decide to travel to Iran (even as dual citizens) and if arrested in Iran, their adopted country and its citizenship are considered secondary by IR. Therefore, their adopted country, in essence, is powerless to do a great deal to help them. Of course, their adopted country can lodge a protest, etc... but those arrested are considered Iranians.
3) If an Iranian (especially by birth) decides to travel to Iran with his/her U.S. or otherwise passport, he/she will have to apply for a VISA from the IR Embassy or Consulate. Now, unless the applicant has a different “place of birth” other than Iran mentioned in his/her passport, then IR will know that he/she is in fact Iranian under IR law. Of course, they can either grant the VISA or refuse to do so.
In summary, the main difference is between being born in Iran vs. being a naturalized American or whatever. The father’s birthplace plays a critical role too as far as IR law is concerned.