How long did it take to travel the 4K miles? The article didn’t mention.
Below is the speed of our Navy’s newest UGM-133A Trident II, or Trident D5. The Navy fired 4 of these off shore by Vandenberg in Febuary, this year.
UGM-133A Trident II, Speed: Approximately, 18,030 mph (29,020 km/h) (Mach 24; 8,060 m/s)[1](terminal phase).
Range: Operational Range:
More than 7,456 miles (12,000 km)[6][7] (exact is classified)[8].
https://en.wikipedia.org/wiki/UGM-133_Trident_II