Obama says terror threat has ‘evolved into a new phase’

President Barack Obama used a rare Oval Office address to try to reassure an anxious public in the wake of the California shootings that the United States can deal with an "evolving" threat of terrorism.

In the televised prime-time speech on Sunday night, Mr Obama said that attacks like the San Bernardino shootings that left 14 dead underscored how the terrorist threat had “evolved into a new phase.”

He vowed to stick with his strategy to beat the Islamic State militants and did not announce any dramatic changes to the US-led campaign of air strikes against the group in the Middle East.

"We should not be drawn into a long and costly ground war in Iraq and Syria, " said Mr Obama, pointing out that Isis wanted to maintain insurgencies, to kill US soldiers and to draw new recruits.

Facing a public that has lost confidence in his ability to beat Isis, Mr Obama acknowledged the concern, saying that many ask “whether we are confronted by a cancer that has no immediate cure.”

“The threat of terrorism is real, but we will overcome it,” he said in his 13-minute address from a lectern in the Oval Office.

This was only Mr Obama’s third televised address from the office and the first in five years, reflecting the White House’s concern about the public nervousness around the threat of further attacks.

A CNN/ORC poll before the president’s address said 60 per cent of Americans disapproved of his handling of terrorism and 68 per cent said the response to Islamic State had not been aggressive enough.

Calling the San Bernardino shooting “an act of terrorism designed to kill innocent people,” Mr Obama said there was no evidence US-born Syed Rizwan Farook or his Pakistani wife Tashfeen Malik were directed by an overseas group or part of a broader conspiracy at home.

“It is clear that the two of them had gone down the dark path of radicalisation, embracing a perverted interpretation of Islam that calls for war against America in the West,” he said.

The FBI is investigating whether Malik posted a message on Facebook pledging allegiance to Islamic State during the attacks.

Mr Obama compared their attack with shootings in Fort Hood, Texas and Chattanooga, Tennessee and the Boston Marathon bombing, saying that "terrorists turned to less complicated acts of violence" as the US had become better at preventing complex, multifaceted attacks.

“As the internet erases the distance between countries, we see growing efforts by terrorists to poison the minds of people like the Boston Marathon bombers and the San Bernardino killers,” he said.

In his address, Mr Obama stressed the importance of gun control, saying the US had to “make it harder” for militants to kill by making it more difficult to buy assault rifles like the ones used in San Bernardino.

Referring to Republican criticism of his campaign against the group and the caustic anti-Muslim rhetoric of the presidential campaign, the president said that destroying Islamic State would not depend on “tough talk or abandoning our values, or giving into fear.”

“We will prevail by being strong and smart, resilient and relentless and by drawing upon every aspect of American power,” he said.

Mr Obama urged Americans not to play into the hands of Islamic State by alienating Muslims with suspicion and hate.

“We cannot turn against one another by letting this fight be defined as a war between America and Islam,” he said, describing Islamic State as “thugs and killers, part of a cult of death.”

Equally, Muslims cannot deny the existence of an extremist ideology that has spread within some of their communities, Mr Obama said.

“This is a real problem that Muslims must confront, without excuse,” he said.

Donald Trump, the frontrunner in the Republican presidential polls, chided the president for the length and content of his address, tweeting: "Is that all there is? We need a new president - fast!"

Another Republican candidate Jeb Bush called for a more aggressive strategy against Islamic State.

“President Obama has finally been forced to abandon the political fantasy he has perpetuated for years that the threat of terrorism was receding,” he said.