US Secretary of State John Kerry arrived in Baghdad on Wednesday as part of a Middle East tour hoped to build regional support for efforts to defeat extremist Sunni militants the Islamic State (IS).

Kerry travelled to Iraq from Jordan, which had been the first stop in a trip that will include Saudi Arabia and see him attempt to pull together a coalition to take on IS. The militant group overran large parts of northern Iraq in June then declared a caliphate in the land it controls. It has since committed a number of war crimes and atrocities, including the mass killing of prisoners and beheading of two American journalists.

Saudi, a Sunni powerhouse in the region, will host talks on Thursday between Kerry and ministers from 10 Arab countries — including the Gulf states, Egypt, Jordan and Lebanon — as well as Turkey, on joint action against IS. Nine mostly European countries had previously been named as the core of a coalition which US President Barack Obama said would take on the militants.

Kerry is expected to speak with Iraq's new Prime Minister Haidar al-Abadi, who formed a inclusive government designed to push back against the IS this week, something the US secretary of state described as a "major milestone". The US hopes that Haider's new government will boost the Iraqi response against IS by engaging support from Iraq's Sunnis and Kurds, many of which felt alienated and targeted under former premier Nouri al-Maliki's divisive rule.

Meanwhile, Obama will lay out his plan to defeat the militant group in an address to the nation later on Wednesday.

Obama's address, which will take place at 9pm EST, is expected to see him make clear the extent of the effort which will be required to defeat IS and admit that the process could take years. "I think the American people need to expect that this is something that will require a sustained commitment," White House spokesman Josh Earnest said, in remarks carried by AFP .

The president has spent his time in office attempting to disentangle the US from wars in Iraq and Afghanistan, but IS's recent advances have meant that the US now sees action as a necessity.

Earnest added that Obama would outline a strategy to "degrade and destroy" IS. Details of how he intends to achieve this, however, are currently unclear, although the president will reaffirm that conventional ground troops will not be sent back to Iraq, according to officials cited by Al Jazeera.

A major question will be whether an ongoing series of American airstrikes hitting IS targets in Iraq will be broadened to Syria. Obama has so far avoided action in Syria, despite official acknowledgement that it will be required to beat the jihadi militants. This may be because of fears that strikes could boost support for IS, but is also likely because of the complex situation on the ground. The US opposes embattled Syrian President Bashar al-Assad — whose troops are also fighting IS in some parts of the country — and cautiously backs secular rebels opposed to both Assad and IS.

However, the New York Times quoted a senior official as saying that airstrikes in Syria would not be an option, while the Washington Post cited a foreign policy expert who recently met the president as saying the US is willing to attack the militants "wherever their strategic targets are". There appears to be public support. An opinion poll conducted for the Post and ABC News showed aerial attacks in Syria would be supported by 65 percent of Americans versus the 71 percent who supported them in Iraq.