Former foes, President Barack Obama and Russian President Dmitry Medvedev, have signed a landmark agreement to reduce both countries' nuclear arsenals.

The new strategic arms limitation treat will cut nuclear weapons supplies in the U.S. and Russia by a third over the next seven years.

"It includes significant reductions in the nuclear weapons we will deploy," President Obama explained. "It cuts our delivery vehicles by roughly half. It includes a comprehensive verification regime, which allows us to build further trust."

CBN News spoke with Cliff May of the Foundation for the Defense of Democracies about Thursday's agreement.  Click play to watch.

The biggest nuclear arms pact in a generation will drop the number of nuclear warheads held by Russia and the U.S. to 1,550 apiece.

The signing comes just days after the administration announced the U.S. would not use nuclear weapons against non-nuclear states, even if they were to attack America with chemical or biological weapons.

"If any state eligible for this assurance were to use chemical or biological weapons against the United States or its allies or partners, it would face the prospect of a devastating conventional military response," Defense Secretary Robert Gates said.

Just weeks after signing the largest domestic spending bill in history, the president has made one of the biggest foreign and defense policy changes in the past 50 years.

But not everyone is happy.

"Folks on the left are really going to be upset that this doesn't go farther in the dismantling of nuclear weapons," political analyst Rick Klein claimed. "And on the right they're going to see this as laying down arms in the middle of a pretty intense fight with neighbors around the world."

Critics also believe the agreement is flawed because it doesn't include China, which is a growing military power.

The treaty isn't binding until it's ratified by the U.S. Senate and the Russian parliament. That means the president's next mission will be to sell it to lawmakers and the country.