Washington: Even as its 13-year-long war in Afghanistan comes to an end this month, America continues to face 'security challenges' around the globe, in particular from the sudden rise of ISIS, President Barack Obama has said.

"Even as our combat mission ends in Afghanistan, there are still challenges to our security around the globe. In times of crisis, people around the world look to one nation to lead, and that is the United States of America," Obama told a group of US troops on their return from war-torn Afghanistan.

"Even our critics, when they get into trouble, they're calling us. And when the world calls on America, we call on you - our men and women in uniform - because nobody can do what you do," said the US President.

In Iraq, he said, local forces have held the line in some places and pushed back ISIS in other places.

"In Syria, our airstrikes are inflicting heavy losses on ISIS fighters and leaders. Because of you, we have blunted their momentum and we have put them on defencive," he said.

"These terrorists are learning the same thing that the leaders of al-Qaeda have learned the hard way. They may think that they can chalk up some quick victories, but our reach is long. We do not give up. You threaten America, you will have no safe haven. We will find you. And, like petty tyrants and terrorists before you, the world is going to leave you behind and keep moving on without you," he said.

Noting that the campaign in Iraq will take time, Obama said, "Our coalition isn't just going to degrade this barbaric terrorist organisation, we're going to destroy it."

"These terrorists only know how to destroy. We know how to do something bigger - how to build the security and peace and justice that we can build with others," he said.

Thanking the returning US soldiers from Afghanistan, Obama said the war in Afghanistan would come to an end this month.

"This month, in just two weeks, the transition that we're making in Afghanistan will be complete. Afghans will take full responsibility for their security and America's war in Afghanistan will come to a responsible end," he said.

"That doesn't mean everything is great in Afghanistan. It is still a very dangerous place," he said.

"Despite all their challenges, Afghans are now looking to the future. That's all because of you," he said.

The President assured Afghans of the continued support of the US even after its combat mission ends.

"We'll continue to have a limited military presence there because we've got to keep training and equipping Afghan forces, and we've got to conduct counter-terrorism missions because there are still remnants of al-Qaeda there," he said.

"We want a stable and secure Afghanistan. And, we want to make sure that country is never again used to launch attacks against the US," Obama said.