Speaking at the National War College in Washington where he marked the 20th anniversary of the Nunn-Lugar Cooperative Threat Reduction Program, Obama addressed reports Syrian President Bashar Assad has considered using chemical warheads as a last-ditch effort to squash the rebellion in his country.
"And today, I want to make it absolutely clear to Assad and those under his command: The world is watching," Obama intoned. "The use of chemical weapons is and would be totally unacceptable. And if you make the tragic mistake of using these weapons, there where be consequences, and you will be held accountable."
At the same time, Obama opened a door for closer cooperation with Russia, which has been allied with Syria.
"Russia has said that our current agreement hasn't kept pace with the changing relationship between our countries. To which we say, let's update it," Obama said. "Let's work with Russia as an equal partner. Let's continue the work that's so important to the security of both our countries. And I'm optimistic that we can."
Obama said despite "some very tough fiscal choices" his administration has during the past four years and will continue in the coming years to fund nuclear, chemical and biological weapons reduction efforts.
"We simply cannot allow the 21st century to be darkened by the worst weapons of the 20th century," the president said.
"That's why I continue to believe that nuclear terrorism remains one of the greatest threats to global security. That's why working to prevent nuclear terrorism is going to remain one of my top national security priorities as long as I have the privilege of being president of the United States."