Media playback is unsupported on your device Media caption President Obama said the US was hitting so-called Islamic State "harder than ever"

The US is hitting so-called Islamic State (IS) harder than ever, President Barack Obama has said.

More air strikes were launched against the group in November than in any other month, he said in a Pentagon speech.

In recent weeks, the US-led coalition has killed a number of its leaders and attacked the oil facilities it uses to finance its operations, he added.

Mr Obama has been seeking to reassure the public following an attack in California that killed 14 people.

The two suspects were a radicalised Muslim couple who struck weeks after the killing of 130 people by Islamist gunmen in Paris.

Around 9,000 air strikes have been launched against the group since the start of the campaign in the summer of 2014.

Noting that IS had lost 40% of the territory it once controlled in Iraq, Mr Obama said that the terror group had not had a single successful ground operation in either Syria or Iraq since the summer.

He cautioned that the US and its partners faced "a very tough fight ahead".

Image copyright Getty Images Image caption The UK Parliament voted earlier this month to conduct air strikes in Syria as part of the coalition

Mr Obama listed the militant group's leaders who had been targeted and killed.

Using another acronym for the group, he said: "The point is, Isil leaders cannot hide and our next message to them is simple: 'You are next.'"

Among those listed was Mohammed Emwazi, a Kuwaiti-born British militant known as Jihadi John, who appeared in videos of the beheadings of Western hostages and who was killed last month.

On Thursday, the president will visit the National Counterterrorism Center in Virginia where he is expected to receive a briefing and then speak.

The two visits come as Mr Obama tries to reassure a wary US public of his strategy against the militant group.

Just over a week ago, he gave a major televised speech with the same objective and to warn against anti-Muslim sentiment.

Image copyright EPA Image caption Mr Obama spoke at the Pentagon with a number of senior officials, including Defense Secretary Ashton Carter, who will soon depart for a Middle East trip

Critics of his strategy continue to ratchet up pressure.

House Majority Leader Kevin McCarthy, a Republican, said on Monday: "It's obvious that the president's current strategy isn't working.

"Far from being contained - much less defeated - Isis has now extended the reach of its terror farther than ever before."

In recent weeks, US fears of a terror attack have swelled, with about 70% of Americans saying the risk of an attack in the US is at least "somewhat high".