Baghdad: Iraqi forces launched a string of attacks on militants on Tuesday, including at Saddam Hussein's hometown Tikrit, as US President Barack Obama declared his firmest commitment yet to targeting militants.
Kurdish and federal forces, who wrested back control of the country's largest dam, battled militants 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 militants 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.
The dam was the biggest prize yet clawed back from the Islamic State (IS) militant group since it launched a major offensive in northern Iraq in June, sweeping aside Iraqi security forces.
"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.
US and other officials have repeatedly stressed that military cooperation between the Kurds and Baghdad was essential to any successful counter-offensive but their alliance remained uneasy.
"We are the ones who liberated the dam, not the peshmerga," said one of several members of the federal special forces who climbed on top of two vehicles to shout at journalists gathered at a Kurdish checkpoint near Badriyah, on the edge of Mosul Lake.
Fighting erupted on Tuesday in the area surrounding the dam and US warplanes carried out fresh strikes targeting IS, a senior officer in the Kurdish peshmerga forces said.
US experts had warned that a breach of the dam could result in a flood wave 20 metres (yards) tall at the city of Mosul to its south and cause flooding along the Tigris River all the way down to Baghdad.
As anti-militants forces tried reclaim ground lost earlier this month in the north, the government launched an operation to recapture the city of Tikrit, further south.
"The Iraqi army and volunteers, backed by Iraqi helicopters, are taking part" in the operation to retake the hometown of executed former president Saddam Hussein, a high-ranking army officer said.
Tikrit fell on June 11 and has since been controlled mostly by militant groups, including former members of Saddam's ruling Baath party.
The government, whose forces folded when militants swept across five provinces more than two months ago, has made Tikrit a priority but has already failed twice to retake it.
US military aircraft have carried out 35 air strikes against IS militants in Iraq over the past three days, destroying more than 90 targets, the Pentagon said.
Obama justified the strikes, the first US military intervention since troops withdrew in 2011, with the risk of genocide against the Yazidi minority and a threat to US personnel in the Kurdish capital of Arbil.
Washington has so far resisted growing calls in and outside Iraq to expand its air strikes beyond targets in the north.
In their latest social media effort, IS supporters started the hashtag "#AmessagefromISIStoUS" to mark posts on microblogging site Twitter, threatening the United States with remarks such as: "We will drown all of you in blood."
It was hijacked by American users who retorted with jingoistic rhetoric, including one user who posted a picture of a drone firing missiles along with the message: "This drone is for you".
In a statement dated on Sunday, IS warned that the United States "will soon disappear... at the hands of the knights of the Caliphate."
The militants 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".
Two months of violence have brought Iraq to the brink of breakup, and world powers are relieved by the departure of divisive premier Nuri Al Maliki, who stepped down last week, hoping his successor will be a unifying figure.
In the north, members of minority groups including Christians, Yazidis, Shabak and Turkmen, remain under threat of kidnap or death at the hands of the militants, rights groups say.
Amnesty International, which has been documenting mass abductions in the Sinjar area, says IS fighters have kidnapped thousands of Yazidis in this month's offensive.