According to the Iraqi President (prime minister?) the General was an invited guest, bearing an official response from the Iranian government to an Iraqi proposal aimed at de-escalating the tensions between Iran and the Saudis. The Mango Mussolini, in launching the drone strike, has assassinated a de-facto diplomatic courier, engaged on a diplomatic mission on the soil of a host country.
This violation of the 1961 Vienna Convention will have the result of painting a bullseye on the back of every US and UK diplomat around the world (I include the UK because our shitstick government is very likely to back US actions) and make them legitimate targets for retaliation. Way to go, Donny! Bigly winning!