Argentina and the United States have maintained bilateral relations since the United States formally recognized the United Provinces of the Río de la Plata, the predecessor to Argentina, on January 27, 1823. Relations were severely strained in the era of World War II, when Argentina refused to declare war on Nazi Germany, and became the only Latin American nation not to receive American aid. Relations continued to be difficult when the Perons were in power. Relations were strained in 1982 after the US supported the United Kingdom against Argentina. Since 1998, Argentina has been a major non-NATO ally, partly owing to Argentina's assistance to the United States in the Gulf War. Relations have been strained at times over the past few years, especially during the Cristina Fernández de Kirchner administration, but they have improved since President Mauricio Macri came to power in late 2015. Country comparison History After Argentina became independent from Spanish rule, the United States formally recognized the United Provinces of the Río de la Plata, the legal predecessor to Argentina, on January 27, 1823. The bilateral relations have seesawed over the last century and a half between periods of greater cooperation and periods of tension over ideology and finance. There has never been a threat of war. Argentine leaders were disappointed when the American government refused to invoke the Monroe Doctrine during instances such as the British establishment of a colony on the Falkland Islands, or during the Anglo-French blockade of the Río de la Plata. In 1833 US Navy shells the Falkland Islands, at the time under Argentine control, in retaliation for the seizing of American ships fishing in Argentine waters. The new constitution of 1853 was based in part on the American Constitution. In 1853, a commercial treaty was concluded between the two nations. 1870–1930 Argentina was closely linked to the British economy in the late 19th century; and as such there was minimal contact with the United States. When the United States began promoting the Pan American Union, some Argentines were suspicious that it was indeed a device to lure the country into the US economic orbit, but most businessmen responded favorably and bilateral trade grew briskly after the United States and did care of duties on Argentine wool in 1893. Relations soured when Argentina refused to join the Allies in the First World War. Argentina had large British and German populations and both