BAGHDAD: Iraqi forces battled jihadis on several fronts Thursday and were poised to receive the help of 450 extra U.S. troops slated for deployment near Ramadi.

Washington's decision to send more advisers and trainers to Iraq failed however to silence critics who say the White House lacks a strategy to combat ISIS.

A year after a jihadi-led offensive saw the government lose control over swathes of Iraq, military operations to weaken ISIS were experiencing mixed fortunes.

The autonomous Kurdistan region's peshmerga forces pushed south and west of Kirkuk on the back of intensive bombing by Iraqi and U.S.-led coalition warplanes, security officials said.

One of the targets was a bomb-making workshop ISIS had set up after their main car bomb factory in nearby Hawijah was completely levelled in a coalition airstrike last week, one official said.

The June 3 strike caused an explosion that was heard 50 kilometers (30 miles) away and destroyed what some officials said was ISIS' largest such plant in Iraq and Syria.

Iraqi federal troops and the Popular Mobilization - an umbrella for mostly Shiite militias and volunteers - also continued operations aimed at securing Baiji, north of Baghdad.

The area has seen relentless fighting over the past year and Iraqi forces in recent days achieved some progress in pushing ISIS fighters out of the town of Baiji as well as from the nearby refinery, the country's largest.

Anti-ISIS forces launched a wide-ranging military operation early Thursday to clear "the last Daesh [ISIS] pockets along the Tigris River" around Baiji, an army major general said.

Establishing firm control over Baiji is seen as key to isolating ISIS in the vast western province of Anbar, whose reconquest is Baghdad's declared priority.

The jihadis beat the government to the punch however, seizing provincial capital Ramadi on May 17 and dealing Baghdad its worst setback in almost a year.

Prime Minister Haider al-Abadi vowed to swiftly retake Ramadi but operations have been sluggish and questions are still being asked about the security forces' ability following their chaotic retreat from the city.

U.S. President Barack Obama Wednesday approved the deployment of 450 more troops to Iraq, in what would nudge the ranks of Washington's "train, advise and assist" mission past 3,500.

The new U.S. training contingent will be based at Taqaddum Air Base, nestled along the Euphrates between jihadi-held Ramadi and Fallujah.

"There is always a risk whenever we're in Iraq that we could be hit with indirect fire, as we have in the past, that we could be attacked," said senior Pentagon official Elissa Slotkin.

The fall of Ramadi last month was not just a blow to Baghdad but also to Washington's strategy in tackling an ultraviolent group whose appeal has kept growing, making it a global threat.

The U.S.-led coalition has carried out close to 4,500 airstrikes since August 2014 and undertaken trainings to reform a security apparatus that completely folded when ISIS swept in a year ago.

Obama, who admitted the United States did not "yet have a complete strategy" has come under intense criticism for allowing chaos to spiral in the region.

"I support the tactical move the president is taking, but where's the overarching strategy,?" said House of Representatives Speaker John Boehner, reacting to the announcement on the latest Anbar reinforcements.

The Soufan Group risk consultancy said seven years of U.S. military presence following the 2003 invasion and billions of dollars had not prevented disaster.

"Immediately after the fall of Mosul, the focus was on re-training the Iraqi military, with the ethos of 'helping them fight their own fight' - ignoring that almost limitless resources had already been thrown at this issue and that the policy had failed every true test," it said.

Several officials in Anbar said Thursday that Iraqi and foreign warplanes had bombed targets in and around Ramadi.

Baghdad's operations so far have focused on severing IS supply lines in Anbar, which has a long border with regions of Syria the jihadi group also controls.

Abadi has said a ground operation inside Ramadi was made too dangerous by the jihadis' use of truck bombs.