In this article Gwen Dyer is thankful that the Iranians attacked and kidnapped British troops rather than Americans. She is concerned that belligerent Americans when attacked would defend themselves causing a larger conflict. (I’m not sure why anyone would say defending oneself from an armed attack would be belligerent.)
Of course the reason the reason the Iranians attacked the British is because they knew the Brits would not fight back. Weakness like this invites attacks by truly belligerent powers. When a nation like Iran knows that there adversaries will fight beck they are not as likely to act aggressively. In reality American “belligerence” works to maintain peace.