Some of the 1,500 new US troops authorized to “advise and train” Iraqi forces in their fight against the Islamic State of Iraq and Syria (ISIS) militants will be deployed in Iraq within the next few weeks without waiting for Congress to fund the mission, the Pentagon said on Thursday.

Meanwhile, clashes broke out all over the city of Ramadi, one of the last urban areas partly under the Iraqi government control in Anbar, when ISIS militants attacked the city from all sides.

Rear Admiral John Kirby, the Pentagon press secretary, said leading elements of the US force would begin moving to Iraq in the coming weeks, even if Congress has not yet acted on a $۵.۶ billion supplemental request to fund the expanded fight against the militants who overran northwestern Iraq earlier this year.

Large swathes of land in Iraq have become ISIS strongholds as the extremist group, which declared a "caliphate" in the territory it seized in Iraq and Syria, drove Iraq's army – the recipient of $۲۵ billion in US training and funding since the 2003 invasion – to collapse.

In late October, the Pentagon revised its estimate of the cost of the US air war in Iraq and Syria, saying the price tag for the campaign against ISIS comes to about $8.3 million a day.

Since US airstrikes began on August 8, the campaign – which has involved about 6,600 sorties by US and allied aircraft – has cost the US $580 million, said Pentagon spokesman Commander Bill Urban.

In addition, the campaign, which has so far failed to stop ISIS advances, has also cost the Iraqi government $260 million.

Officials initially indicated they needed to get lawmakers to approve the funding for the troops deployment before the Pentagon could start the mission, but General Lloyd Austin, the head of US troops in the Middle East, recommended starting the effort using resources already available to him.

"The commander ... can reallocate resources inside his theater as he deems fit. So he is going to .. try to get a jump start on this program," Kirby told reporters, adding that congressional approval of the $5.6 billion was still needed to carry out the "more robust program."

The Pentagon’s announcement came just days after US officials said some 50 troops had been sent to Ain al-Asad air base in Anbar province in Iraq to establish an operation to “advise and train” Iraqi troops.

Kirby said Austin thought that starting the expanded mission sent a message both to Iraqis and other coalition partners.

"It sends an important signal ... about how seriously we're taking this," Kirby said. "The sooner we get started, the sooner Iraqi units will improve ... and the sooner we'll get coalition contributions to that particular mission."

Kirby indicated additional US troops would begin deploying to Iraq before the end of the year.

"You're going to start to see initial elements of the 1,500 or so additional start to flow in the next few weeks," he said. "I think certainly by the end of the calendar year you're going to see a much more robust presence, not just by the United States doing this but by coalition partners as well."

US President Barack Obama, who was elected in 2008 largely due to his promises to exit Middle Eastern military entanglements – especially in Iraq – and avoiding new ones, announced plans last week to double the number of American troops in Iraq, approving an additional 1,500 forces to establish sites to “train” nine Iraqi military brigades and three Kurdish peshmerga brigades.

The move came almost three years after US troops completed their withdrawal from Iraq after a nine-year occupation that left the country in turmoil.

Iraq ranked first out of 162 countries on the Global Terrorism Index, the Australia and US-based Institute for Economics and Peace (IEP) said in a report published Tuesday, giving the country a score of 10 out of 10.

According to the report, 80 percent of the lives lost to "terrorist" attacks in 2013 occurred in just five countries – Iraq, Afghanistan, Pakistan, Nigeria and Syria.

The influx in "terrorist" attacks raises questions about the effectiveness of the US "War on Terror" launched by the Bush administration after the 9/11 attacks, which included the US invasions of Iraq and Afghanistan.

The campaign failed to eliminate or even reduce terrorism, as the report showed a steady increase in the death toll over the last 14 years, from 3,361 in 2000 to 11,133 in 2012 and 17,958 in 2013.

On the contrary, the campaign in general and the US invasion of Iraq in particular served as a recruitment tool for terrorist groups, such as ISIS, as figures show that terrorism rose precipitously in Iraq since 2003.

Ramadi under fire

The recent expansion of terrorist groups in the Anbar province raises questions about the effectiveness of the US anti-terrorism strategies in Iraq, as the western province was the main battleground between US Marines and al-Qaeda during the "surge" campaign in 2006-2007.

On Friday, ISIS gunmen fired at an Iraqi government building in central Ramadi, Anbar's capital, local officials said, after the militants launched a sudden attack on the city.

"ISIS launched a sudden attack from four directions – north, west, east and south of Ramadi," a police first lieutenant in the city told AFP by phone.

He said the jihadists had also detonated car bombs targeting Iraqi security forces.

"Clashes are ongoing around the city. A series of mortar attacks have targeted areas inside the city, including provincial council buildings and a police post," the officer said, adding that it was too early to estimate the number of casualties.

"Mortar fire has been continuous since midnight," police captain Qusay al-Dulaimi said.

Council member, Mohammed Mahmoud, said security forces and tribal fighters were preventing the militants from advancing from Mualimeen towards the government complex.

Hathal al-Fahdawi, a local council member for the western province of Anbar, said gunmen were firing from rooftops of buildings in Mualimeen neighborhood into central Ramadi.

Mosques in the city, according to Fahdawi, “are asking anyone who can carry weapons to confront the attackers.”

Moreover, Fadhawi said ISIS fighters took over the village of al-Shujairiya, about 20 kilometers east of Ramadi, where a tribal leader said security forces killed 12 militants who tried to storm a mosque and a house near the village.

Losing the provincial capital would be a setback for the Iraqi army after they broke an ISIS siege of the country's largest refinery this week and hoped to gain critical momentum in the battle against the militants.

ISIS claims Erbil suicide bombing

The US-led anti-ISIS campaign has so far failed to stop ISIS from gaining ground, thus drawing criticism from many sides, including the president of the Iraqi Kurdistan autonomous region, Massoud Barzani.

On Wednesday, following a suicide bombing that hit the usually secure capital of Iraq’s autonomous Kurdish region, Barzani accused Western countries of not providing enough heavy weapons to help peshmerga forces deliver a "decisive blow" against ISIS militants.

Later on Thursday, ISIS claimed responsibility of the suicide attack in an online statement.

"We breached all the security checkpoints of the agent Kurdistan government and reached the heart of the city of Erbil," the statement said.

It identified the bomber as Abdul-Rahman al-Kurdi, indicating that he was an ethnic Kurd.

The bomber struck the main checkpoint on the way to the provincial government headquarters in the northern city just before noon on Wednesday, killing four people and wounding more than two dozen.

The bombing was the worst attack to hit Erbil since September 29, 2013, when militants struck the headquarters of the Asayesh security forces in the city, killing seven people and wounding more than 60.

In that attack, the Asayesh said a suicide bomber detonated explosives at the entrance to their headquarters, after which they killed four more would-be bombers before a fifth blew up an ambulance rigged with explosives.

Kurdish peshmerga forces joined the battle against ISIS in August after the extremist group targeted ethnic and religious minorities, took control of the country's largest dam and moved within striking distance of Erbil, where many Western expatriates, including oil industry and aid workers are based.