US Secretary of State John Kerry has warned Iraqi Prime Minister Nuri al-Maliki not to cause trouble as Washington threw its weight behind President Fuad Masum.

“We stand absolutely squarely behind President Masum (who) has the responsibility for upholding the constitution of Iraq,” he said during his visit to Sydney this week.

“Our hope is that Mr. Maliki will not stir those waters.”

his comments come after DefenceMinister David Johnston has not ruled out Australia backing up the US in Iraq, warning the situation with ISIL could turn “very nasty” quickly.

“We’re not ruling out providing some backup assistance to the Americans if they go in and deal kinetically with this terrorist organisation,” he told ABC Radio today.

“This ISIL Islamist state terrorist organisation is to be extremely feared and to be taken with great seriousness.

“Who knows what the future holds with these people.

“We are we are ready to assist in whatever way we can should we be asked to assist by the Americans and the Iraqi government.”

The Minister said the situation could turn “very, very nasty” in a “very short space of time”.

“I think anything’s to be expected.

“I don’t believe right minded countries can just sit back and watch atrocities unfold on their nightly television without taking some action.”

Crews are starting to pre-position ready to “slot in” and drop supplies over Mount Sinjar, he said.

Australia is “very good at the art of doing humanitarian drops,” Senator Johnston added, citing the experience of missions over East Timor in the late 1990’s.

The Minister said the potential for airlifts is “still in a planning phase”, with talks being held with the US.

TROOPS SEAL OFF BAGHDAD’S GREEN ZONE

Troops loyal to controversial Iraqi PM Nouri al-Maliki have sealed off Baghdad’s “Green Zone” as he appeared on national television to denounce his political opponents.

Embattled Prime Minister Nouri al-Maliki, in a surprise speech at midnight Iraq time (7am AEST), resisted calls for his resignation and accused the country’s new president of violating the constitution, plunging the government into a political crisis at a time it is battling advances by Islamic State militants.

Al-Maliki is seeking a controversial third-term as prime minister, but the latest crisis has prompted even his closest allies to call for his resignation.

A parliament session scheduled for today to discuss the election and who might lead the next Iraqi government was postponed until August 19.

In the nationally televised speech, al-Maliki declared he will file a legal complaint against the new president, Fouad Massoum, for committing “a clear constitutional violation.”

In the hour before his speech, special forces units loyal to his political party reportedly took up positions in key Baghdad locations — including bridges and the international airport.

Al-Maliki, whose Shiite-dominated bloc won the most seats in April elections, accused Massoum - an ethnic Kurd - of neglecting to name a prime minister from the country’s largest parliamentary faction.

President Masum theoretically had 15 days after his July 24 election to pick a prime minister.

Al-Maliki’s Shiite coalition won April polls comfortably but his standing has been undermined by a devastating jihadist offensive launched on June 9 that overran large swathes of Iraq.

Al-Maliki has accused the president of violating the constitution “for the sake of political goals.”

The Prime Minister himself has been repeatedly accused of serving only the interests of his on Shiite faction and actively suppressing the voices and interests of other Iraqi ethnic and religious groups.

The United States has repeatedly pressed for his resignation to allow for the formation of a strong “unity” government to lead the fight against Islamic State advances.

There isn't an actual coup, Baghdad is calm. Maliki has raised the stakes through his statement, it's the Iraqi form of poker (or chicken) — Sajad Jiyad سجاد (@SajadJiyad) August 10, 2014

POLITICAL TURMOIL

Al-Maliki, speaking on Iraqi TV for the first time since US forces launched air strikes and humanitarian airdrops in Iraq last week, said the security situation will only worsen as a result of Massoum’s actions.

As his forces took position around Iraq’s capital, he accused his political opponents of being the ones conducting a coup.

“This attitude represents a coup on the constitution and the political process in a country that is governed by a democratic and federal system,” al-Maliki said. “The deliberate violation of the constitution by the president will have grave consequences on the unity, the sovereignty, and the independence of Iraq and the entry of the political process into a dark tunnel.

The political infighting could hamper efforts to stem advances by Sunni militants who have seized a large swath of northern and western Iraq in recent weeks.

Yes Maliki got the votes, but he is not supported by parliament. Not perfect but that's how it works. He can't just hold on & threaten all — Sajad Jiyad سجاد (@SajadJiyad) August 10, 2014

LOSS OF SUPPORT

President Barack Obama warned Americans on Saturday that the new campaign to bring security in Iraq requires military and political changes and “is going to be a long-term project.”

Obama said Iraqi security forces need to revamp to effectively mount an offensive, which requires a government in Baghdad that the Iraqi military and people have confidence in. Obama said Iraq needs a prime minister — an indication that suggests he’s written off the legitimacy of the incumbent, al-Maliki.

Critics say the Shiite leader contributed to the crisis by monopolising power and pursuing a sectarian agenda that alienated the country’s Sunni and Kurdish minorities.

Just hours after al-Maliki’s speech, the US State Department said it “fully supports” the new Iraqi president.

State Department spokeswoman Jen Psaki said in a statement the US supports the process to select a prime minister “by building a national consensus and governing in an inclusive manner.” She said the US rejects any effort to use coercion or manipulation in the process of choosing a new Iraqi leader.

Fully support President of #Iraq Fuad Masum as guarantor of the Constitution and a PM nominee who can build a national consensus. — Brett McGurk (@brett_mcgurk) August 10, 2014

MILITARY ADVANCES

The US air strikes have reinvigorated Kurdish forces battling the Islamic State militants in northern and western Iraq. Kurdish forces retook two towns from the Sunni militants yesterday, achieving one of their first victories after weeks of retreating, a senior Kurdish military official said.

Kurdish Peshmerga fighters were able to push the militants of the Islamic State group out of the villages of Makhmour and al-Gweir, some 45 kilometres from the Kurdish capital of Irbil, Brigadier Gen. Shirko Fatih said.

The United States launched a fourth round of air strikes Sunday against militant vehicles and mortars firing on Irbil as part of efforts to blunt the militants’ advance and protect American personnel in and around the Kurdish capital.

US warplanes and drones have also attacked militants firing on minority Yazidis around Sinjar, which is in the far west of the country near the Syrian border.

In the Kurdish capital yesterday, the president of the semi-autonomous Kurdish Regional Government, Massoud Barzani, said American military support has been effective thus far, but, he added, Peshmerga soldiers require more firepower to defeat the militants.

“We are not asking our friends to send their sons to fight on our behalf,” Barzani told The Associated Press in a brief interview. “What we are asking our friends is to provide us support and to cooperate with us in providing us with heavy weapons that we are able to fight this terrorist group.”

INTERNATIONAL BACKING

Barzani met yesterday with French Foreign Minister Laurent Fabius, who travelled to Baghdad and Irbil pledging France’s commitment to providing humanitarian aid. Fabius also met with al-Maliki and called on Iraqi leaders to unite in the face of the escalating crisis.

“The marching order is solidarity,” Fabius said. He called on Iraqis to form a “government of broad unity so that all Iraqis feel represented and together lead the battle against terrorism.”

A week ago, Al-Maliki ordered the Iraqi air force to support Kurdish forces against the militants, in a rare instance of cooperation between Baghdad and the Kurdish regional government, which have for years been locked in disputes over oil and territory.

REFUGEES ESCAPE

Meanwhile, thousands of Yazidi refugees fleeing the militants continued to pour across the border from Syria into Iraq after a weeklong journey through blazing hot mountains. Followers of an ancient religion with links to Zoroastrianism, the Yazidis said the militants had given them the choice of converting to Islam or dying.

As they crossed the border, many Yazidis said they had lost sisters, daughters, young children and elderly parents during the trip. They said militants sprayed gunfire at fleeing crowds, sometimes splitting up families by taking the women and killing the men.

Video from U.S. military airdrop of food, water Aug. 9 for thousands of Iraqi citizens threatened by ISIL in Iraq: http://t.co/vfdPNemugh — U.S. Central Command (@CENTCOM) August 11, 2014

It was not clear how many Yazidis were missing. In the span of 30 minutes, about a dozen displaced Yazidis approached one journalist, pleading for assistance to find their loved ones.

British officials estimated Saturday that 50,000 to 150,000 people could be trapped on Sinjar Mountain, where they fled to escape the Islamic extremists, only to become stranded there with few supplies.

Britain said its air force has already dropped water containers and solar lanterns over the mountains.

During his Sunday blessing at the Vatican, Pope Francis expressed outrage at the violence aimed at religious minorities in Iraq and called on the world “to stop these crimes.”

He cited “the thousands of people, including Christians, who have been brutally forced from their homes, children who have died from thirst during the escape and women who have been seized.”

He also spoke of “the destruction of religious, historic and cultural treasures.”

In a statement issued Sunday, the European Union said it was “appalled by the rapid deterioration of the humanitarian situation, with hundreds of thousands civilians, mainly from minorities, fleeing the areas of conflict.”

Some of the militants’ acts “may constitute crimes against humanity and must be investigated swiftly, so that the perpetrators are held accountable,” the EU said.

#BreakingNews Eyewitnesses: More army enforcements and hundreds of soldiers are now being deployed across all of #Baghdad. #Iraq #ISIS — Rami (@RamiAlLolah) August 10, 2014