Internally, Thailand grappled with the ramifications of its alliance with Japan. This alliance was not universally accepted within the country and led to the formation of the Seri Thai Movement, which supported the Allies and resisted Japanese influence. Social challenges included managing the repercussions of forced labour for wartime projects and dealing with the scarcity of resources. Politically, maintaining a balance between Japanese pressure and internal dissent was a significant challenge, as was the task of preserving the semblance of sovereignty under increasing Japanese oversight.

The war acted as a catalyst for nationalism and modernisation in Thailand. Nationalistic policies, previously seeded by the government, were amplified as the war necessitated a unified national front. This period also saw the acceleration of modernisation efforts, albeit under duress, such as the development of infrastructure. The social fabric of Thailand was also rapidly evolving, with greater roles for women emerging out of necessity as men were conscripted for the war, and with heightened awareness of international affairs among the populace.

Post-war, Thailand's economy faced the monumental task of transitioning from a wartime footing to peacetime normalcy. This involved restructuring industries that had been repurposed for military use, dealing with the devastation of infrastructure, and stabilising the economy amidst inflation and resource shortages. The government implemented policies to encourage economic growth and invested in reconstruction efforts. However, challenges included rebuilding trade relationships that had been severed or strained during the war and addressing the economic disparities that had been exacerbated by the conflict.

Thailand's wartime experience had a profound impact on its post-war foreign policy. After initially siding with Japan, Thailand's quick realignment with the Allies at the end of the war showcased a strategic flexibility that would characterise its foreign relations in the subsequent Cold War era. The necessity of negotiating with the Allies for recognition and aid informed a diplomatic approach that was cautious, pragmatic, and aimed at maintaining as much autonomy as possible. This period also set the precedent for Thailand's role as a regional intermediary and its participation in broader international organisations.

At the onset of the war, Thailand maintained a delicate neutrality but was coerced into partnership with Japan following a brief conflict and subsequent armistice. As the war progressed, Thailand became a de facto ally of Japan, receiving promises of regained territories. The relationship was complex, marked by Thai cooperation but also by a degree of manipulation as Japan utilised Thai resources for its war efforts. By the end of the war, the relationship soured as the reality of Japan's failing campaign became apparent, prompting Thailand to re-establish relations with the Allied powers.