A missile of that range would need to fly on a very highly lofted trajectory to have such a long flight time.
Assuming a range of 950 km, then a flight time of 37 minutes would require it to reach a maximum altitude of more than 2,800 km (1700 miles).
So if the reports are correct, that same missile could reach a maximum range of roughly 6,700 km (4,160 miles) on a standard trajectory.
That range would not be enough to reach the lower 48 states or the large islands of Hawaii, but would allow it to reach all of Alaska.
There is not enough information yet to determine whether this launch could be done with a modified version of the Hwasong-12 missile that was launched on May 14.