US President Barack Obama will announce later tonight that the US will begin airstrikes against Islamic State militants "wherever they exist".
In an address to the country, he will confirm that the US will lead an international campaign to stop the Islamic State organisation, both inside and outside of Iraq.
"It will not involve American combat troops fighting on foreign soil," Mr Obama said in excerpts of the speech.
He will say that the US will "lead a broad coalition" with a clear objection to "degrade and ultimately destroy" the group through a "comprehensive and sustained counter-terrorism strategy".
Mr Obama will announce that the US will use its air power in a "steady, relentless effort to take out" the Islamic State group "wherever they exist", signalling that the US will pursue IS in Syria.
The United States will also support national forces on the ground in the region.
The President will describe a counter-terrorism strategy that will not involve US combat troops but will be more along the lines of their actions recently in Yemen and Somalia.
The President's speech begins at 2am Irish time.
Earlier, Mr Obama authorised $25 million in "immediate military assistance" for the Iraqi government and Kurdistan Regional Government to help with military education and training.
The announcement was made on the White House website.
US Secretary of State John Kerry has endorsed Iraqi Prime Minister Haider al-Abadi's plans to mend Baghdad's relations with Sunnis and Kurds.
He also described Iraq as a partner in the fight against Islamic State militants.
Mr Kerry, on a tour of the Middle East to build military, political and financial support to defeat the militants controlling parts of Iraq and Syria, said: "We all have an interest in supporting the new government of Iraq."
"The coalition that is at the heart of our global strategy I assure you will continue to grow and deepen in the days ahead... because the United States and the world will simply not stand by to watch as ISIL's evil spreads," he said, using an alternative acronym for Islamic State.
"A new and inclusive Iraqi government has to be the engine of our global strategy against ISIL. Now the Iraqi parliament has approved a new cabinet with new leaders, with representation from all Iraqi communities, it's full steam ahead," Mr Kerry said.
Mr Kerry's visit comes hours before a speech by President Barack Obama on taking on the threat of IS, backed by what Washington hopes will be a coalition of NATO and Gulf Arab allies committed to a campaign that could stretch beyond the end of Mr Obama's term in 2016.
Mr Obama spoke to Saudi Arabia’s King Abdullah bin Abdulaziz on the matter this afternoon.
"When the world hears from President Obama this evening, he will lay out with great specificity each component of a broad strategy of how to deal with ISIL," Mr Kerry said.
Mr Kerry told Mr Abadi he was encouraged by his plans for "reconstituting" the military and his commitment to political reforms reaching out to all of Iraq's religious and ethnic communities.
Mr Abadi formed his government on Monday in what was billed as a break from the more abrasive style of his predecessor Nuri al-Maliki, whose policies were blamed by many Iraqis for fuelling sectarianism and pushing the country to the brink of collapse.
Islamic State fighters seized large chunks of Iraq's north and west this year, welcomed by many of the Sunni Muslim minority, who blamed the government for targeting them with indiscriminate arrests and discriminatory policies.
Mr Abadi appealed to the international community to help Iraq fight Islamic State, urging them "to act immediately to stop the spread of this cancer."
In a sign of the eagerness among Iraq's political elite for a fresh start, new Parliament Speaker Selim al-Jubouri, a Sunni, told Mr Kerry: "We are ... hopeful that we will be able to defeat terrorist organisations and establish democracy in Iraq."
Mr Kerry will meet Jordan's King Abdullah later today, and travel tomorrow to Saudi Arabia for talks that will include Egypt, Turkey, Jordan and the Gulf Cooperation Council(GCC), which comprises Saudi Arabia, Bahrain, the United Arab Emirates, Kuwait, Oman and Qatar.
French President Francois Hollande will travel to Baghdad on Friday ahead of a conference of regional and international powers in Paris on Monday to coordinate efforts to tackle Islamic State.
France said today it would take part in military air action against Islamic State militants in Iraq if necessary.
Foreign Minister Laurent Fabuis said taking any military action against the group in Syria would be done under different "modalities."
"In Iraq ... we will take part in military air action if necessary. The situation in Syria is different" he told students in a speech at the Sciences Po academy in Paris.
"Some in the media say France is ready to act in Iraq, but not Syria. No! We must act in both cases, but not with the same modalities."
Mr Fabius said Syrian President Bashar al-Assad could not be a partner in the fight against Islamic State as he was complicit with the militants.
"That is why we will continue to help the moderate Syrian opposition that is fighting Islamic State and Assad at the same time," he said.
