Kristensen believes that the chances are “very good” that the two leaders will overcome the challenges they face in finalizing the treaty and meet the deadline.

The START treaty should be seen in two contexts, he said.

“One is to get down from the enormous levels of the nuclear weapons that characterized the relationship between the US and Russia during the Cold War,” he said. “That’s what we are still working on. This treaty is still very much a step in that direction.”

“It’s also about trying to change the future relationship between Russia and the US so that their relationship is not so much focused on the strategic balance between the two, and that type of really Cold War-way of looking at each other,” Kristensen said.

However, at some point in the future, he said, it “will be necessary to try to get other nuclear weapon states involved in negotiations.”

Otherwise, “the US and Russia will not be able to go to deep cuts” in their nuclear arsenal.

However, he noted, “Iran and North Korea and those types of powers are in a different category of national security issues that do not relate directly to these large numbers of nuclear forces.”