President Obama: 'Very Difficult' to Detect Lone Wolf Terrorist Plots

— -- Amid his assurance that there is no specific credible threat ahead of the holiday season, President Obama outlined today the difficulty of detecting lone wolf plots such as the attack in San Bernardino, California.

"This is a different kind of challenge," Obama said. "Here essentially you have [ISIS] trying to encourage or induce somebody who may be prey to this kind of propaganda and it becomes more difficult to see."

The president also said the media have “garbled” reporting on the U.S. visa system and that law enforcement and intelligence professionals are “constantly monitoring” public posts, separate from their ability to infiltrate private communications between social media accounts.

"No government is going to have the capacity to read every person’s texts or social media," Obama said, arguing that it "raises questions of our values" between balancing security and privacy interests.

Obama admitted that the Islamic State is “going to continue to be dangerous,” but he assured Americans that the coalition is “going to defeat ISIS” by “systematically squeezing” the terrorist organization -- cutting off its supply line and financing, taking out its leadership and forces, and destroying its infrastructure.

“They are going to be on the run,” Obama pledged.

But Obama was cautious not to guarantee the fight will be without its challenges.

“Whenever I say that we have made progress in squeezing the territory that they control or made real inroads against them what people will say well if something happens around the world then obviously that must not be true,” he said. “But in any battle, in any fight even as you make progress there are still dangers involved.”

Obama said the U.S. “continues to lead” the global coalition’s mission, adding that ISIS, also known as ISIL, is losing its ground in Iraq and Syria.

“As we keep up the pressure, our air campaign will continue to hit ISIL harder than ever, taking out their leaders, their commanders and their forces,” Obama vowed. “Squeezing ISIL's heart at its core in Syria and Iraq will make it harder for them to pump their terror and propaganda to the rest of the world.”

Despite his projected confidence, Obama acknowledged that the threat is real in the homeland, and he urged Americans “to remain vigilant.”

“All of us can do our part by staying vigilant, by saying something if we see something that is suspicious, by refusing to be terrorized, and staying united as one American family,” he said.

With just one year left in the Oval Office, Obama also expressed optimism that he can make 2016 a productive year.

“For all the very real progress America's made over the past seven years, we still have some unfinished business, and I plan on doing everything I can with every minute of every day that I have left as president to deliver on behalf of the American people,” he said. “Since taking this office, I have never been more optimistic about a year ahead than I am right now, and in 2016 I'm going to leave it out all on the field.”

Obama made the remarks in his annual end-of-the-year news conference.

The first family will later fly to San Bernardino on their way to their holiday vacation in Hawaii. The president is expected to meet privately with families of the victims of the Dec. 2 terrorist attack.