[u][b]The Carribbean[/b][/u]
As the Carribbean is a region of entirely island nations, it was affected heavily by the Heavenfall, and the region was then swept through by the WANC following their regrouping in South America. As a result of this the population of the region was drastically reduced, and organised governments in many of the smallest nations were rendered defunct, especially as so many of them had only small and outdated armed forces, reliant on treaties to aid in their defence. 
Precious few nations in the area survived, greater details are provided below.

[i]In this guide, the West Indies are also included as part of the Carribbean region. If an OTL nation is not listed below, it can be assumed to have been rendered ineffectual or destroyed in the Shattered Steel timeline.[/i]

[b]Cuba[/b]
Cuba survived the Heavenfall and the resulting disaster surprisingly well. Further, the collapse of the USSR and Russia did not hinder the country as much as expected. Cuba has remained a socialist country with a planned economy and services provided by the government, such as higher education and universal healthcare, as well as means of production owned and operated by the state. Unlike in many other nations that have tried it over the years, Cuba has been the only relatively successful one, though even then has made several concessions and reorganised and adapted as need be. 
In the wake of the Heavenfall, these reforms became more extensive by necessity, and the Cuban government formed stronger ties with the PRC and the NCAA, both of which assisted in a program of modernisation for the country's ailing infrastructure, and raised the quality of living. This also lead to modernisation of the armed forces. 
One especially notable fact is that the Cuban government expelled the US Navy from Cuba after ending the lease held on the land that Guantanamo Bay occupied, and the base and land reclaimed for use by the Cuban government.

[b]The Bahamas[/b]
The Heavenfall ravaged the Bahamas, and left the country in ruins. Due to the wealth heald in the country in offshore accounts and other capital, it managed to rebuild, but the destruction across the United Kingdom rendered them unable to fulfil their obligations to defend the country from aggression, other than a token show of force to dissuade the WANC. 
As the N/UN was rapidly established, one of the Bahamian Islands - formerly used as a reserve airstrip and flying boat base during the Second World War and early years of the Cold War - was rapidly developed into a fully-fledged military installation including a harbour and habitation and facilities for those living and working on the island, with both air and sea links to other islands of the Bahamas. 
In return, Shattered Steel act as the [i]de facto[/i] defence forces for the Bahamas, as well as providing services such as counter-terrorism, counter-piracy, anti-smuggling, search-and-rescue and reserve air-traffic control, weather surveillance and so on, along with training and instruction for the Bahamian Defence Force itself. 

[b]Jamaica[/b]
Jamaica was heavily affected by the disasters of the Heavenfall. Earthquakes and tidal waves wracked the island nation with destruction, and the resulting fallout from these incidents and disasters further caused damage. In the aftermath, the Jamaican government was forced to rely on foreign aid to rebuild, the process taking a long time. However, this forged greater alliances with the nations of South America, and later the NCAA, when it came to rebuilding the economy and industrial base of the country. PMC's provided by the NCAA also provided security against the WANC and CAA, allowing Jamaica to retain independence and security, and begin to improve its' economic standing. Jamaica has not requested to join the N/UN as yet, and remains an independent nation with friendly ties to the NCAA, Cuba, and the TSA among others.

[b]The Cayman Islands[/b]
The Cayman Islands were all-but destroyed by the seismic and tidal activity of the Heavenfall, with the major centres of population utterly devastated. What people remained were evacuated to nearby safer countries while rebuilding was due to start. 
As such, when the WANC swept through the area, they pillaged the ruins of the Cayman Islands, seizing the territory. George Town is the closest thing that the WANC has to a city or capital, and the Cayman Islands have become their central 'base' of operations, though they maintain a highly distributed and mobile presence across the region.