Washington:
Iraqi forces appear to be rallying and bolstering their defence of Baghdad in the face of Sunni extremists who have swept across the country's north, the Pentagon said on Tuesday.
"We also have reason to believe -- certainly indications -- that the Iraqi security forces are stiffening their resistance and their defence and are coalescing, particularly in and around Baghdad, and that's encouraging," spokesman Rear Admiral John Kirby told reporters.
With Iraqi troops now receiving help from Shiite volunteers, Kirby said "it certainly appears as if they have the will to defend the capital."
The jihadist Islamic State of Iraq and the Levant (ISIL) have staged a stunning advance that has sent the US-trained Iraqi government army into a humiliating retreat, and now Baghdad itself is threatened.
After taking Mosul, the ISIL fighters captured a large area of mainly Sunni Arab territory stretching towards the capital.
The United States spent millions of dollars over several years training and arming a new Iraqi army after disbanding the Sunni-led force created by the late dictator Saddam Hussein.
Last week, Kirby acknowledged the Pentagon was "certainly disappointed in the performance of some of these units."
Iraqi soldiers and police in some cases fled en masse before the insurgent offensive, abandoning their vehicles and uniforms.
Iraqi Prime Minister Nuri al-Maliki sacked several senior officers over the recent defeats, and ordered one of them to face court-martial for desertion.
President Barack Obama has sent troops to Baghdad to strengthen security for the US embassy and is weighing potential military options, including air strikes, to counter the militant onslaught.
Obama has deployed about 170 forces to Baghdad and has another roughly 100 troops at the ready outside of Iraq for various "contingency" operations.
But Kirby said indications that Iraqi troops may be improving their defences did not mean the White House would take more time to weigh potential military action.
He said that "everybody on the national security team understands the sense of urgency there in Iraq and the seriousness of the threat."