BAGHDAD – Islamic State militants disguised in Iraqi army uniforms and driving stolen Humvees killed at least 40 Iraqi soldiers and captured 68 others in western Anbar province, breaking through a deteriorating Iraqi military offensive in an area where the United States recently broadened its airstrike campaign.

The wave of suicide bombings dealt a heavy blow to government efforts to rein in the militants, whose rampage has seized much of the country’s north and west – even as the U.S. and its allies began training Iraq’s Kurdish peshmerga fighters to bolster their ability to battle the Sunni extremists.

The attacks Sunday targeted troops stationed at Camp Saqlawiyah near the town of Sijir, 45 miles (70 kilometers) west of Baghdad. There has been no contact with the 68 captured Iraqi soldiers, who were believed to have been taken to the nearby city of Fallujah, an Islamic State stronghold, said Gen. Rasheed Fleih.

After the attacks, the Iraqi military withdrew 700 more troops stationed in the area, he said.

Following battlefield successes in both Iraq and neighboring Syria, Islamic State fighters, among them many Iraqi nationals, have re-entered Iraq through Anbar province, engaging in fierce battles with the Iraqi military. In this Sunni-majority territory, the group has quickly capitalized on long-standing grievances against the Shiite-led government in Baghdad, earning support from local populations.

Iraq’s new Prime Minister Haider al-Abadi said in a statement Monday that his government is committed to reinforcing military and police forces in Anbar and will increase airstrikes to target the pockets of militant fighters across the province. Last week, he declared an end to the shelling of towns where militants are suspected of hiding, so as not to rile the local populations.

Meanwhile, the U.S. military said Monday that airstrikes on Islamic State targets southwest of the oil-rich northern city of Kirkuk destroyed two military vehicles and a tank and damaged a Humvee, bringing the total U.S. strikes on the militants to 190 since the aerial campaign began on Aug. 8.

Backed by the U.S. airstrikes, Iraqi and Kurdish security forces have retaken the strategic Mosul Dam and several small towns. However, serious challenges remain since many Islamic State fighters are operating from cities with large civilian populations, such as Fallujah and Mosul.

In northern Iraq, meanwhile, the U.S. and its allies began training Kurdish peshmerga forces to enhance their ability to fight the Sunni extremists.

Helgurd Hikmet, general director of the ministry overseeing the Kurdish forces, said that France, Italy and Germany were among countries providing training in the use of the new machine guns, mortars, rockets and demining robots the Kurdish fighters have received.

The U.S. forces are part of the advise-and-assist teams that have been in Irbil, the provincial capital of the semi-autonomous Iraqi Kurdish region, for several weeks. The U.S. has also provided equipment against roadside bombs and other sophisticated artillery to the Kurdish fighters.

Last week, the French joined in the aerial campaign, and a number of European countries have committed to arming the Kurds and providing humanitarian support for more than a million people displaced by the onslaught of the Islamic State group.

The Islamic State group’s spokesman, Abu Mohammed al-Adnani, said that the Islamic extremists were ready to battle a U.S.-led military coalition and called on Muslims worldwide to kill civilians of nations that join the campaign.

“If you can, kill a disbelieving American or European – especially the spiteful and filthy French – or an Australian, or a Canadian, or any other disbeliever from the disbelievers waging war, including the citizens of the countries that joined a coalition against the Islamic State,” al-Adnani said in an audio statement released Sunday.

Late Monday, meanwhile, a car bomb exploded in a commercial district of eastern Baghdad, killing 12 people and wounding at least 28 others, police and hospital officials said.

The attack brought the day’s death toll in and around Baghdad to 26. A bombing and a shooting earlier in the day killed seven, while a midday bomb in a commercial street in Baghdad’s southwestern district of Bayaa killed four people and wounded 13, according to police officials. They spoke on condition of anonymity because they were not authorized to release the information.

Also, just north of Baghdad, gunmen broke into the house of an anti-militant Sunni fighter, killing his two sons and a daughter, the police said. The Sunni fighter was wounded, along with his wife. He was a member of Sahwa, a Sunni militia that joined U.S. troops in the fight against Iraq’s al-Qaida branch at the height of Iraq’s insurgency in 2007 and 2008.

Janssen reported from Irbil, Iraq. Associated Press writers Sameer N. Yacoub and Vivian Salama in Baghdad contributed to this report.