At a press conference on Thursday at the Pentagon, US President Barack Obama said that two years of the US-led air and ground campaign against the "Islamic State" (IS) militant group in Syria and Iraq had shown it could be beaten in conventional military combat.

"I am pleased with the progress that we've made on the ground in Iraq and Syria," Obama said, but added: "We're far from freeing Mosul and Raqqa."

Obama also cautioned on working with Russia. "The US remains prepared to work with Russia to try to reduce the violence and strengthen our efforts against ISIL and al Qaeda in Syria, but so far Russia has failed to take the necessary steps," Obama said, using an alternative acronym for the militant group.

He added that he was not confident Russia or its president, Vladimir Putin, could be trusted.

Small-scale attacks

Speaking to the press on his birthday, Obama said IS still had the ability to carry out damaging small-scale attacks.

"What ISIL has figured out is that if they can convince a handful of people or even one person to carry out an attack on a subway, or at a parade or some other public venue, and kill scores of people as opposed to thousands of people, it still creates the kinds of fear and concern that elevates their profile," he said.

The president said the US had to improve its operations in disrupting terror networks and intercepting online messages to troubled individuals which were encouraging them to act.

"Those networks are more active in Europe than they are here, but we don't know what we don't know, and so it's conceivable that there are some networks here that could be activated," he said, while warning against over-reacting to such attacks.

"They've seen the degree of attention they can get with smaller-scale attacks using small arms or assault rifles," Obama said. "The possibility of either a lone actor or a small cell carrying out an attack that kills people is real."

Over the last month, IS has claimed responsibility for several attacks against civilians in France and Germany.

"How we react to this is as important as the efforts we take to destroy ISIL, prevent these networks from penetrating," Obama said. "When societies get scared they can react in ways that undermine the fabric of our society."

Birthday celebrations

Obama celebrated his 55th birthday on Thursday at a restaurant on the Georgetown waterfront. Obama and his family leave on Saturday for their summer vacation, spending a fortnight at Martha's Vineyard in Massachusetts.

His vice president, Joe Biden, expressed his birthday wishes via Twitter:

jm/cmk (Reuters, AP)