Iraqi forces battled Sunni militants along a string of fronts today, including at Saddam Hussein's hometown Tikrit, as the United Nations readied a massive aid operation for displaced Iraqis.
Kurdish and federal forces, who wrested back control of Iraq's largest dam, fought jihadists in the country's north, buoyed by intensifying US air strikes and Western arms deliveries.
Other security forces backed by militiamen and tribesmen are also fighting jihadists in flashpoints north, west and south of Baghdad, officials said.
The counter-offensives against the militants came as the UN refugee agency said it was launching a major operation this week to help "close to half a million people" who have been displaced.
The dam was the biggest prize yet clawed back from the Islamic State (IS) jihadist 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)," said Obama.
"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 key to any successful counter-offensive, but their alliance remains 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.
Fighting erupted today in the area surrounding the dam and US warplanes carried out fresh strikes targeting IS, a senior officer in the Kurdish peshmerga forces told AFP.
US experts have warned 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-jihadist forces tried to reclaim ground lost earlier this month in the north, the government launched an operation to recapture the city of Tikrit, further south.