BEIRUT—The killing of two American troops and a British soldier in a rocket assault in Iraq has drawn contemporary consideration to the hostile surroundings facing U.S. forces there, placing the county again in the crosshairs of the rumbling conflict in between Washington and Iran.

The U.S. has blamed related attacks in the earlier on professional-Tehran militias, together with Kataib Hezbollah, which congratulated the perpetrators powering the hottest strike on Wednesday for targeting what it named the “U.S. occupation.” The team claimed the U.S. need to bear the…