US warplanes carried out their first air strike on the Islamic State near Baghdad, as world diplomats pledged Monday to support Iraq in its fight against the militants.The United States early last month began air strikes against IS positions in northern Iraq, but Monday`s announcement that the campaign had targeted the jihadists near the Iraqi capital marks an escalation in the scope of the mission.It comes less than a week after US President Barack Obama, in a primetime television address to the nation, ordered a "relentless" war against the Islamic State, including air strikes in Syria and expanded operations in Iraq to "destroy" the marauding jihadist army."US military forces continued to attack ISIL (IS) terrorists in Iraq, employing attack and fighter aircraft to conduct two air strikes Sunday and Monday in support of Iraqi security forces near Sinjar and southwest of Baghdad," US Central Command said in a statement."The air strike southwest of Baghdad was the first strike taken as part of our expanded efforts beyond protecting our own people and humanitarian missions to hit ISIL targets as Iraqi forces go on offense, as outlined in the president`s speech last Wednesday."