8:32 p.m. EST December 15, 2014   America's military commitments are at a "turning point," President Obama told troops Monday, but a "leaner" force will remain ready to defend the security of the nation and the world.

"When the world calls on America, we call on you — our men and women in uniform — because nobody can do what you can do," Obama told servicemembers stationed at Joint Base McGuire-Dix-Lakehurst in New Jersey.

Though the nation will end combat operations in Afghanistan this month, Obama said, the United States remains committed to that embattled country.

A residual force will remain in Afghanistan because it remains "a very dangerous place," Obama said, threatened by the kind of terrorists who plotted the 9/11 attacks more than 13 years ago. U.S. troops will continue to train their Afghan counterparts and help with counterterrorism operations because "remnants of al-Qaeda" still threaten the country.

The end of combat operations in Afghanistan comes a few years after the end of combat operations in Iraq. Obama said that when he took office in early 2009, the U.S. had 180,000 troops in Iraq and Afghanistan; by the end of this month, that number will be below 15,000.

Obama told the troops that the days of major commitments of "large ground forces" for purposes of "nation building" are coming to an end, to be replaced by more targeted missions.

"Going forward, our military will be leaner," Obama said. "But as your commander in chief, I'm going to make sure we keep you ready for the range of missions that we ask of you. We are going to keep you the best-trained, the best-led, the best equipped military in the history of the world, because the world will still be calling."

Two new missions are ongoing, Obama said: efforts by the United States and allies to eradicate the Ebola virus in West Africa, and to defeat the Islamic State jihadist group in Iraq and Syria.

Referring to the Islamic State, Obama said the campaign will "take time." But he added "make no mistake: Our coalition isn't just going to degrade this barbaric terrorist organization; we're going to destroy it."

In delivering a holiday-time "thank you" to the troops, Obama said, "There are people who are alive today because of what you guys are doing. That's American leadership."

Obama thanked troops who are just returning from Afghanistan and said the country will help them readjust to life stateside.

"To all our troops far from home and their families for the holidays," he said, "you're in our thoughts, our prayers, and we can't wait until you come home, too."

Obama called Joint Base McGuire-Dix-Lakehurst one of the nation's premier military bases, featuring members of the Army, Navy, Air Force, Marines and Coast Guard.

"Everybody's here," he said.

The president was joined by New Jersey's two Democratic senators — Bob Menendez and Cory Booker — and the state's Republican governor, Chris Christie, a potential GOP candidate for president in 2016.