What would the United States do ?

If Iran crossed into Iraq, tried to kidnap 5 US soldiers, Killed 2, Injured 2 and took 1 hostage and brought him back to Tehran.

What would the US do ?
I have a feeling it wouldnt be as strong as the Israeli Campaign

palestinians have fired thousands of rockets into israel, blow themselves up in tel aviv every few days and the majority of them support terrorists and want all the jews dead all the while they would all stave to death if it wasn't for israel giving them money

i think israel is showing immense self-restraint in their actions