U.S. President Barack Obama says "American leadership is the one constant in an uncertain world."
Obama said Saturday in his weekly address that America is taking a leadership role in several of the world's most pressing challenges, including the fight to degrade and destroy the terrorist group ISIL, and the effort to rally the world against Russian aggression in Ukraine.
The president said America is also taking the lead in the fight to contain and combat the Ebola epidemic in West Africa, and the engagement of more partners and allies to confront the growing threat of climate change "before it's too late."
President Obama said "the people of the world look to us to lead... and we welcome that responsibility."