Vice President Biden on Thursday told Iraqi Prime Minister Nouri al-Maliki the U.S. was prepared to "intensify and accelerate security support" to aid Baghdad after Islamic militants seized two large cities.
In the call, Biden "expressed the United States’ solidarity with Iraq," the White House said in a statement.
The Islamic State of Iraq and the Levant, an al Qaeda affiliate, has taken control of government and military installations in Mosul and Tikrit. Reports said hundreds of thousands of civilians have fled the fighting.
The statement did not say if Biden offered U.S. airstrikes to target the rebel group. Al-Maliki has repeatedly requested airstrikes in recent weeks, according to reports, only to be rebuffed by the administration.
Earlier Thursday, President Obama responded to a question about the possibility of using drone strikes or airpower in Iraq by saying he did not "rule out anything."
“This is an area that we’ve been watching with a lot of concern, not just over the last couple of days, but over the last several months," Obama said.
“I don’t rule out anything because we do have a stake in making sure that these jihadists are not getting a permanent foothold in either Iraq or Syria, for that matter," he continued.
Al-Maliki has been a difficult ally for Washington, abandoning commitments to bring more opposition Sunnis into his government and share oil revenues.
His actions have led to internal strife and an alliance between more moderate Sunnis and radical jihadist groups, which are now pressing the attack against the government.
Earlier Thursday, White House press secretary Jay Carney said "all Iraqi leaders, including Prime Minister Maliki, need to do more to address unresolved issues within Iraq to better meet the needs of the Iraqi people."
"We urge Iraq's leaders to secure support from all Iraqi communities by presenting a common political vision with tangible programs aimed at bringing the country together," Carney said. "This has been an ongoing challenge in Iraq as it tries to build a future as a sovereign state."