President Barack Obama highlighted his administration's many achievements while reaffirming the American people that the U.S. will defeat the Islamic State during his year-end news conference on Friday.

"So much of our steady, persistent work over the years is paying off for the American people in big, tangible ways," Obama said in his opening remarks.

The president spent the hour-long press event touting a number of his 2015 highlights, including his progress in reestablishing ties with Cuba, working with other countries to tackle climate change, and the historic U.S.-Iran Nuclear Deal, which put a halt on Iran's nuclear program.

He also said that 17 million more people received health insurance through his signature healthcare law, the Affordable Care Act. As a result, the number of uninsured people has fallen below 10 percent of the population for the first time in recorded history, he said.

At another point in the conference, he outlined some of the crucial issues he plans to tackle in 2016 before his tenure comes to an end. Those issues include closing the Guantanamo Bay prison and fighting to stop the Islamic State terror group, commonly known as ISIS.

"We are going defeat ISIS," Obama said, adding that U.S. airstrikes in Syria and Iraq were hitting the group "harder than ever" while killing ISIS leaders and commanders.

He warned that the battle against ISIS, however, would not be easy as the terror group continues to inspire lone wolves and self-radicalized people to carry out attacks in the West.

"It is very difficult for us to detect lone wolf plots or plots involving a husband and wife," Obama said, referring to the attack that killed 14 people in San Bernardino, California, earlier this month.

"It's not that different from us trying to detect the next mass shooter. You don't always see it. They're not always communicating publicly, and if you're not catching what they say publicly, then it becomes a challenge."

Watch the full press briefing below.