WASHINGTON - The killing of Abu Bakr al-Baghdadi in northern Syria by American forces is a boost for President Donald Trump at a time when his foreign policy decisions and claims have been questioned amid an impeachment inquiry conducted by the opposition-controlled House.

While the unrelated impeachment inquiry will rumble on, the successful operation will at least temporarily placate critics - importantly including those like Senator Lindsey Graham from the Republican Party - alarmed that Mr Trump's recent pullback of US troops from north-eastern Syria may create room for ISIS to rebound.