U.S. Jets and Drones Attack Militants in Iraq, Hoping to Stop Advance

The United States launched a series of airstrikes against Sunni militants in northern Iraq on Friday, using Predator drones and Navy F-18 fighter jets to destroy rebel positions around the city of Erbil, the American military said Friday.

The strikes were aimed at halting the advance of militants with the Islamic State in Iraq and Syria toward Erbil, the Kurdish capital, which is home to a United States Consulate and thousands of Americans.

The action marked the return of the United States to a direct combat role in a country it left in 2011. Warplanes dropped 500-pound laser-guided bombs on a number of targets: a mobile artillery piece that was being towed from a truck and had begun shelling Erbil, a stationary convoy of seven vehicles, and a mortar position.

The military also used a remotely piloted drone to strike another mortar position on Friday afternoon. After the first strike, it said in a statement, ISIS militants “returned to the site moments later” and “were attacked again and successfully eliminated.”

Defense officials expressed confidence that they could achieve within a few days one of President Obama’s stated goals: stopping the advance of the militants on Erbil.

Less certain was whether the other objectives Mr. Obama had announced — breaking the siege on tens of thousands of refugees stranded on Sinjar Mountain and protecting Americans in Baghdad — could be achieved as quickly, given the instability of Iraq’s internal politics and the difficulty of protecting and eventually evacuating the stranded people.

While Mr. Obama said Thursday night that he had authorized military strikes, if necessary, to help liberate the refugees on Sinjar Mountain, all of the military attacks on Friday were directed toward stopping the ISIS militants’ advance on Erbil.

The leader of ISIS sent a defiant message to the Americans in an audio statement posted on YouTube in June and recirculated on Twitter on Friday.

“This is the message of the leader of the faithful,” the leader, known as Abu Bakr al-Baghdadi, wrote in a message addressed to “America, the defender of the cross.”

“You should know, you defender of the cross, that getting others to fight on your behalf will not do for you in Syria as it will not do for you in Iraq,” he said. “And soon enough, you will be in direct confrontation — forced to do so, God willing. And the sons of Islam have prepared themselves for this day. So wait, and we will be waiting, too.”

ISIS fighters had come within 25 miles of Erbil in a rapid advance that took American military planners by surprise.

Rear Adm. John Kirby, the Pentagon spokesman, said in a statement that ISIS fighters near the mortar positions had been “successfully eliminated,” although he did not say exactly how many had been killed. Another Defense Department official said that the precision of the laser-guided bombs dropped was such that in the case of the strike on the stationary convoy, “you know that vehicle and the people in it don’t exist anymore.”