lands southward from the Nation and undertook measures to maintain internal tranquility in such areas, the United States on the other hand withdrew from interposition in Mexico. European powers largely regarded these matters as the concern of the United States. Indeed, the nascent Pax Americana was, in essence, abetted by the policy of the United Kingdom, and the preponderance of global sea power which the British Empire enjoyed by virtue of the strength of the Royal Navy. Preserving the freedom of the seas and ensuring naval dominance had been the policy of the British since victory in the Napoleonic Wars. As it was not in the interests of the United Kingdom to permit any European power to interfere in Americas, the Monroe Doctrine was indirectly aided by the Royal Navy. British commercial interests in South America, which comprised a valuable component of the informal empire that accompanied Britain's overseas possessions, and the economic importance of the United States as a trading partner, ensured that intervention by Britain's rival European powers could not engage with the Americas. The United States lost its Pacific and regionally bounded nature towards the end of the 19th century. The government adopted protectionism after the Spanish–American War and built up the navy, the "Great White Fleet", to expand the reach of U.S. power. When Theodore Roosevelt became President in 1901, he accelerated a foreign policy shift away from isolationism towards foreign intervention which had begun under his predecessor, William McKinley. The Philippine–American War arose from the ongoing Philippine Revolution against imperialism. Interventionism found its formal articulation in the 1904 Roosevelt Corollary to the Monroe Doctrine, proclaiming the right of the United States to intervene in the affairs of weak states in the Americas in order to stabilize them, a moment that underlined the emergent U.S. regional hegemony. By 1900, the United States possessed the world's largest industrial capacity and national income, having surpassed both the United Kingdom and Germany. Interwar period The United States had been criticized for not taking up the hegemonic mantle following the disintegration of Pax Britannica before the First World War and during the interwar period due to the absence of established political structures, such as the World Bank or United Nations which would be created after World War II, and various internal policies, such as protectionism. Though, the United States participated in the Great War, according to Woodrow Wilson: [...] to