Children in ISIS-captured Mosul
Children in ISIS-captured Mosul Reuters

The White House said over the weekend it was ready to "take action" against any threat to America as it indicated serious consideration of U.S. military strikes against the Islamic State (IS, formerly called ISIS) in Syria, AFP reports.

The Pentagon has warned of the dangers of IS and said operations against it in Syria may be needed, after weeks of air strikes have slowed the advance of the Sunni group in Iraq.

The White House also said late Friday that air strikes in Syria may be necessary, as deputy national security advisor Ben Rhodes agreed that "any strategy to deal with the ISIS organization has to deal with both sides of the border, Iraq and Syria."

"If we see plotting against Americans, we see a threat to the U.S. emanating from anywhere, we stand ready to take action against that threat," Rhodes added, according to AFP.

"We've made very clear time and again that if you come after Americans, we're going to come after you wherever you are, and that's what's going to guide our planning in the days to come," he declared.

On Thursday, Defense Secretary Chuck Hagel said that the IS poses an “imminent threat” to the United States and may take years to defeat.

“They are an imminent threat to every interest we have, whether it’s in Iraq or anywhere else,” Hagel said.

Islamic State “is as sophisticated and well-funded as any group that we have seen,” he added.

IS declared itself a "caliphate" in late June and has since added a swath of northern Iraq to territory it already held in eastern Syria.

President Barack Obama has launched a campaign of air raids to help regional Kurdish and Iraqi forces fighting IS in the country's north.

This week, IS threatened to attack Americans "in any place" if U.S. airstrikes in Iraq hit its people.

A video published by the group featured a statement which said in English "we will drown all of you in blood".