Well, it violated international law. As long as they weren't engaged in military operations the American vessels had every right to be in Iranian waters under the doctrine of "innocent passage" without being molested by the Iranians.
Yet supporters of Mr Obama have been quick to praise the Administration's spineless response to Iran's criminal act by claiming- falsely- that we would have done the same thing were an Iranian vessel to stray into American waters under the same circumstaces.
Fascinating, isn't it, how quick some Americans are to side with America's enemies against their own country?
HT; Real Clear World