By 1968, quite a few nations had joined what was sarcastically refereed to as the "fat man club". While fusion boosted weapons were still a monopoly of the big two (USA/USSR, despite what they say about their allies and fellow countries), it had proven fairly easy to obtain the informtion and infrastructure to jumpstart a basic Fat-man plutonium bomb, or, if refining was the issue, a uranium little-boy or a Debner tactical nuke. In many cases, they were purchased whole on the black arms market, or even successfully salvaged from battlefields or wrecks.
Some minor unaligned clashes had already involved battlefield atomics and in three cases, larger fat-man size weapons used on cities, generally against non-armed neighbors to terminate conflicts (Montevideo, Kampala and and Falan). It was clear that for the smaller or non-aligned countries, an A-bomb, any A-bomb, was vital to ensure national sovereignty, much as a dreadnaught was in 1910.
As a result, no-one was suprized when Brazil and India announced that they would be holding a series of collaborative underground nuclear tests in both countries. many regarded this as a propaganda ploy, showing the collaboration of the two major non-aligned nations. Additionally, adding UN observers was seen as little more than a publicity ploy, as was the insistence on the testing being underground; both countries and the UN had been pushing for a moratorium on above ground tests due to the already major biosphere damage from the nuclear conflicts of the past twenty years.
The suprise came when the test shots, six of them, occurred early, and almost simultaneously; more surprising was the realization that they were in fact, massive cannons using 150kt nuclear charges to loft over 15,000 tons of equipment and self deploying structures into orbit. Three major Orbital command stations were quickly manned and finished off by crews waiting in orbit under cover of the UN orbital clearance forces which had been clearing wreckage and debris in orbit since 1963. Within twenty four hours, the heavily armored and armed stations were weapons operational, and with the existing clearance craft had captured and deactivated or destroyed all non-UN orbital assets. While the crews were small and initially had to live in their spacesuits (crew quarters were a lower priority than weapons) , they were invulnerable.
As the blindsided superpower alliances attempted to respond, conventional/kinetic weapons impacted in the near vicinity of all the NATO/PACT nearside lunar bases, and within uninhabited areas of the superpower homelands. With minimal casualties, and near total surprise, the UN and Non-aligned nations had seized the high ground.
The UN peacekeeping directorate, aka PAX, took command and declared all cislunar space and lunar nearside to be a demilitarized disarmed area under its jurisdiction, backed by an estimated 200 orbital nuclear weapons, some claimed to be as large as the 1953 Moscow busters. Both superpowers blustered, and both learned that the threat was real when military groundside assets were hit by nuclear weapons; a brief attempt to destroy the stations failed partly due to lack of cooperation, and partly due to the fact that a 5000 ton armored and heavily defended station was a much tougher nut to crack than the earlier platforms proven so vulnerable in the previous wars. Finally, too, when station two was critically damaged by one of the few joint strikes, the Nuclear Cannons (aka Verne Guns) lofted a cloud of simple but deadly unmanned ageis hunter killers (aka killer crowbars); soon after, a fourth station was also was lofted and deployed. East and West were forced to the negotiating table, much as Burma and Urugay had been, and with equal humiliation and desire for revenge.
The terms PAX imposed by the treaty of the Azores were simple. Cislunar space was declared a demilitarized exclusion; military craft and platforms were forbidden, and all other assets in orbit were open to inspection at any time. Military craft were similarly forbidden, except for transit through the exclusion zone. Use of nuclear weapons Earthside were forbidden on pain of massive reprisal, initially nuclear, but later from the lunar mass cannons that PAX constructed. It was also noted that the Verne cannons did not have to deliver their payloads to orbit.
By 1970, kicking an screaming, the superpowers had been dragged into a cold, conventional standoff Earthside and in orbit, although arsenals for deterrence began growing at a prodigious rate. While far from safe, the immediate threat of nuclear holocaust was at least delayed, and local space made free for all. Unfortunately, the solar system would be the next area of conflict.
Next: Yes, at last we come to one of the two eras for an RPG campaign !