The United States has taken the first step in its planned expanded fight against Islamic State militants, engaging in airstrikes near Baghdad on Monday to aid Iraqi security forces who were being attacked by enemy fighters, U.S. officials said Tuesday. Since early August, the number of air strikes has increased to 162.

Less than a week after President Barack Obama pledged a multi-step campaign to degrade and destroy ISIS militants, U.S. attack and fighter aircraft were used Sunday and Monday to carry out targeted air strikes in Sinjar to the north and southwest of Baghdad in support of Iraqi offensive operations, the Associated Press reported.

After assistance was requested by Iraqi forces, U.S. aircrafts stepped in, U.S. officials said on condition of anonymity since they were not authorized to discuss the mission publicly.

Obama, who will be briefed Wednesday by defense officials at U.S. Central Command in Tampa, Fla., authorized new airstrikes last week aiming to help Iraqi forces on the offensive against the Islamic militants, Voice of America reported. He also said potential airstrikes could occur in Syria, but ruled out working with Syrian President Bashar al-Assad against the IS group, which is fighting to topple him.

Previously, airstrikes in Iraq had been used to protect U.S. personnel, carry out humanitarian missions, assist Iraqi refugees and secure critical infrastructure.

Meanwhile, after Obama asked Congress to step in and authorize the training of moderate Syrian rebels,  U.S. House of Representatives will meet in Washington D.C. Tuesday to debate on legislation that will give congressional approval for arming and training rebels opposed to both IS and the Syrian government.

The authority comes under Title 10 of the U.S. code, which deals with military powers, and Congress could vote on granting it this week, according to CNN. Approval also would allow the United States to accept money from other countries for backing the Syrian opposition forces.

"We've seen public statements from Democrats and Republicans in senior positions both in the House and the Senate indicate they support giving the administration the necessary authority to ramp up our assistance to the Syrian opposition by training and equipping them. So, we're gratified by that show of bipartisan public support for this urgent priority," White House spokesman Josh Earnest said.

Over the weekend, U.S. Secretary of State John Kerry courted Middle Eastern leaders to join an international coalition that would include airstrikes, ground forces, and cutting off funding for the militants.

About 30 countries, including the Arab League, the European Union and United Nations, have pledged to join the United States in fighting against ISIS militants who have taken over parts of Iraq and Syria, carried out atrocities against religious minorities, and beheaded three Western hostages, according to VOA.