The biggest thing for Japan is that "there are North Korean medium-range missiles" aimed at them, and that North Korea has been kidnapping Japanese citizens.
"Japan [also] wants to see reduced friction on the Korean Peninsula," Baker said, adding that "they don't really want a strong, unified Korea, which would be economically competitive with them, militarily competitive with them."
In the long term, however, Japan "would like to be able to shift their military attention away from worrying about North Korea, and back to the strategic issue they have with China," he said, adding that that's "why they've been flirting with Russia."
"Japan has a little bit of a tough time here," Baker said. "They've to a great degree been left out of this batch of dialogue."