The war has also been attributed to the after-effects of colonialism in South America, with border conflicts between the new states, the struggle for power among neighboring nations over the strategic Río de la Plata region, Brazilian and Argentine meddling in internal Uruguayan politics (which had already caused the Platine War), and Solano López's efforts to help his allies in Uruguay (previously defeated by the Brazilians), as well as his presumed expansionist ambitions.