Here's why:
* The war is the driving force behind the characters' suffering and displacement. The novel explores the impact of the Second World War on a group of displaced people, including refugees and soldiers. The war has taken their homes, loved ones, and sense of normalcy.
* The war creates an atmosphere of fear, violence, and uncertainty. This atmosphere permeates the lives of the characters and shapes their actions and decisions.
* The war's presence is omnipresent. Even in the midst of their personal struggles, the characters are constantly reminded of the war's devastation and the fragility of their lives.
While the war is the primary antagonist, there are also secondary antagonists who contribute to the characters' hardships:
* The oppressive regime: The novel touches upon the oppressive political regime in Sri Lanka during the war years, which further disrupts the lives of the characters.
* The characters' own internal struggles: The characters grapple with trauma, loss, and guilt, which can be seen as internal antagonists hindering their healing and growth.
Ultimately, the true antagonist in "Swallowing Stones" is the confluence of forces – the war, the oppressive regime, and the characters' internal struggles – that shape their experiences and the story itself. It's the interplay of these factors that creates the complex and poignant narrative that Ondaatje weaves.