Information era Bomber upgrade.

As fighters got faster and more lethal, for a brief period jet bombers were considered necessary by Cold War air forces … until intercontinental ballistic nuclear missiles promised the ability to rain destruction on distant cities with less fuss. The United States designed the XB-70 Valkyrie, for instance, to carry nuclear warheads across the pole to Russia – only two were ever built. The B-1 Lancer was somewhat more successful; with a speed of Mach-2 it could (hopefully) outrun the nuclear blast so the crew might survive – about 100 of the B-1B version were put in service as “low-level penetrators.” But in general, the old B-52s and Soviet Su series worked just as well (although their attack would be a one-way trip), and were a lot cheaper. In modern air forces, the distinctions between bombers, fighter-bombers and fighters have blurred considerably, such that most aircraft in service today could be considered “jet bombers.”