Soviets start sending cosmonauts to the Moon in mid-late 1970s, to establish a base there before the Americans. Program takes dozens of missions over at least a decade. One of the missions involves a mishap and the crew is stranded on the lunar surface and/or in orbit. Rescuing them becomes an international effort (USA, USSR, China, France, etc.) and the recovery mission is a success. Aftermath results in a global space administration, under which individual countries still retain control of their space programs.
Construction of the moon base continues with cooperation between USA and USSR, completes initial structures and layout by the mid 1990s.
Meanwhile, governments on Earth declare that alternative methods to reaching space need to be established due to massive uptick/volume of rocket launches. Many scenarios proposed, but LEO space stations connected by space elevators becomes the standard, with the eventual goal being an orbital ring circling the equator. Countries along the equator (e.g. Colombia, Brazil, Kenya, DRC/Zaire, Indonesia, etc.) see this as an opportunity to become major players on the global stage, expanding their economies and influence.
The Global Space Initiative (GSI) coordinates efforts by individual nations' space programs to begin establishing working colonies on the lunar surface. The primary goal is research on low-atmosphere colonization.
Many countries are represented. However, as mentioned, those containing space elevators are highly influential in trade and transportation of goods and people to the colonies. This bolsters their economies and strengthens their importance to the GSI.
As the moon begins to see more growth and economic relevance, long-time residents begin to seek independence from the GSI in favor of having their own governing body. Their dependence on Earth's subsidies, while still existing, begins to shrink with the growth of a self-sustaining economy.
Research and space exploration rely heavily on access to the moon, providing a valuable source of revenue and employment.
An increase in the moon's relevance on the global stage begins to create resentment among groups in various countries. This dissatisfaction stems from frustrations with Earth's resources being used to develop the moon instead of being used for improvements to Earth infrastructure.
Groups begin to form to oppose further growth of the colony.
Everything comes to a head when a major terrorist act results in the destruction of nearly every space elevator on Earth's surface.
Not only does this severely hinder the ability for people to travel freely to and from the moon, it also cuts off all trade. The ramifications for Earth are very serious, and even moreso for those on the moon. Those who were only on the moon temporarily are unable to return as planned. Due to security, the GSI puts in place an embargo on any and all travel unless completely necessary.
Particularly on the moon, this day becomes a pivotal moment in history and affects many aspects of everyday life.