Iraqi forces launched a string of attacks on Sunni militants yesterday, including at Saddam Hussein's hometown Tikrit, as US President Barack Obama declared his firmest commitment yet to targeting jihadists.
Meanwhile, the UN refugee agency yesterday said it was poised to mount a massive aid operation for 500,000 Iraqis driven from their homes by jihadist rebels.
"In response to the deteriorating situation in northern Iraq, UNHCR is this week launching one of its largest aid pushes aimed at helping close to half a million people who have been forced to leave their homes," spokesman Adrian Edwards told reporters.
Kurdish and federal forces, who wrested back control of the country's largest dam, battled jihadists in the country's north, buoyed by intensifying US air strikes and Western arms deliveries.
Other security forces backed by militiamen and tribesmen meanwhile launched strikes against the jihadists at numerous flashpoints north, west and south of Baghdad, officials said.
Obama on Monday hailed the recapture of the dam but warned Baghdad that "the wolf is at the door" and said it must move quickly to build an inclusive government.
"This operation demonstrates that Iraqi and Kurdish forces are capable of working together and taking the fight to (IS)," he said.
"If they continue to do so, they will have the strong support of the United States of America," he promised, in his clearest signal yet that the 10-day-old US air campaign was far from over.
Fighting erupted in the area surrounding the dam yesterday and US warplanes carried out fresh strikes targeting IS, a senior officer in the Kurdish peshmerga forces told AFP.
US experts had warned that a breach of the dam could result in a flood wave 20 metres tall at the city of Mosul to its south and cause flooding along the Tigris River all the way down to Baghdad.
As anti-jihadist forces tried reclaim ground lost earlier this month in the north, the government launched an operation to recapture the city of Tikrit, further south.
Tikrit fell on June 11 and has since been controlled mostly by Sunni militant groups, including former members of Saddam's ruling Baath party.
The government, whose forces folded when jihadist-led militants swept across five provinces more than two months ago, has made Tikrit a priority but has already failed twice to retake it.
The jihadists, who declared their "caliphate" over a vast region straddling the Iraq-Syria border, have also came under attack in their Syrian stronghold of Raqa by Syria's air force.
In London, Prime Minister David Cameron said Britain remained open to "supplying equipment" for the fight against IS but told a meeting of his government's emergency committee Cobra that "this is not about getting dragged into a war in Iraq".