World War II

====War breaks out in the Pacific (1941)====
{{main|Pacific War}}
[[File:228 regiment in HK.jpg|thumb|left|Japanese soldiers [[Battle of Hong Kong|entering Hong Kong]], 8 December 1941]]

Following the Japanese [[false flag]] [[Mukden incident]] in 1931, the Japanese shelling of the American [[USS Panay incident|gunboat ''USS Panay'']] in 1937, and the 1937–1938 [[Nanjing Massacre]], [[Japan–United States relations#1937–1941|Japanese-American relations deteriorated]]. In 1939, the United States notified Japan that it would not be extending its trade treaty and American public opinion opposing Japanese expansionism led to a series of economic sanctions—the [[Export Control Act]]s—which banned U.S. exports of chemicals, minerals and military parts to Japan, and increased economic pressure on the Japanese regime.{{r|ibiblio_1940}}<ref>{{cite journal |year=1983 |title=Peace and War: United States Foreign Policy, 1931–1941 |journal=U.S. Department of State Publication |issue=1983 |pages=87–97 |url=https://www.ibiblio.org/pha/paw/ |access-date=17 February 2022 |archive-date=14 January 2022 |archive-url=https://web.archive.org/web/20220114073007/http://www.ibiblio.org/pha/paw/ |url-status=live }}</ref><ref name="ReferenceC">Maechling, Charles. ''Pearl Harbor: The First Energy War''. History Today. December 2000</ref> During 1939 Japan launched its [[Battle of Changsha (1939)|first attack against Changsha]], but was repulsed by late September.{{sfn|Jowett|Andrew|2002|p=14}} Despite [[1939–1940 Winter Offensive|several offensives]] by both sides, by 1940 the war between China and Japan was at a stalemate. To increase pressure on China by blocking supply routes, and to better position Japanese forces in the event of a war with the Western powers, Japan invaded and [[Japanese invasion of French Indochina|occupied northern Indochina]] in September 1940.{{sfn|Overy|Wheatcroft|1999|p=289}}

Chinese nationalist forces launched a large-scale [[1939–1940 Winter Offensive|counter-offensive]] in early 1940. In August, [[Chinese Communist Party|Chinese communists]] launched an [[Hundred Regiments Offensive|offensive in Central China]]; in retaliation, Japan instituted [[Three Alls policy|harsh measures]] in occupied areas to reduce human and material resources for the communists.{{sfn|Joes|2004|p=224}} Continued antipathy between Chinese communist and nationalist forces [[New Fourth Army incident|culminated in armed clashes in January 1941]], effectively ending their co-operation.{{sfn|Fairbank|Goldman|2006|p=320}} In March, the Japanese 11th army attacked the headquarters of the Chinese 19th army but was repulsed during [[Battle of Shanggao]].{{sfn|Hsu|Chang|1971|p=30}} In September, Japan attempted to [[Battle of Changsha (1941)|take the city of Changsha]] again and clashed with Chinese nationalist forces.{{sfn|Hsu|Chang|1971|p=33}}

German successes in Europe prompted Japan to increase pressure on European governments in [[Southeast Asia]]. The Dutch government agreed to provide Japan with oil supplies from the [[Dutch East Indies]], but negotiations for additional access to their resources ended in failure in June 1941.<ref>{{cite web |title=Japanese Policy and Strategy 1931 – July 1941 |website=US Army in WWII – Strategy and Command: The First Two Years |pages=45–66 |url=https://www.ibiblio.org/hyperwar/USA/USA-P-Strategy/Strategy-2.html |access-date=15 May 2013 |archive-url=https://web.archive.org/web/20130106021700/https://www.ibiblio.org/hyperwar/USA/USA-P-Strategy/Strategy-2.html |archive-date=6 January 2013 |url-status=live}}</ref> In July 1941 Japan sent troops to southern Indochina, thus threatening British and Dutch possessions in the Far East. The United States, the United Kingdom, and other Western governments reacted to this move with a freeze on Japanese assets and a total oil embargo.{{sfn|Anderson|1975|p=201}}{{sfn|Evans|Peattie|2012|p=456}} At the same time, Japan was [[Kantokuen|planning an invasion of the Soviet Far East]], intending to take advantage of the German invasion in the west, but abandoned the operation after the sanctions.<ref>{{cite book|last1=Coox|first1=Alvin|title=Nomonhan: Japan against Russia, 1939|date=1985|publisher=Stanford University Press|location=Stanford, CA|pages=1046–1049|isbn=978-0-8047-1835-6}}</ref>

Since early 1941, the United States and Japan had been engaged in negotiations in an attempt to improve their strained relations and end the war in China. During these negotiations, Japan advanced a number of proposals which were dismissed by the Americans as inadequate.<ref name=USAWWIIcp5>{{cite web |title=The decision for War |website=US Army in WWII – Strategy, and Command: The First Two Years |pages=113–127 |url=https://www.ibiblio.org/hyperwar/USA/USA-P-Strategy/Strategy-5.html |access-date=15 May 2013 |archive-url=https://web.archive.org/web/20130525064812/https://www.ibiblio.org/hyperwar/USA/USA-P-Strategy/Strategy-5.html |archive-date=25 May 2013 |url-status=live}}</ref> At the same time the United States, the United Kingdom, and the Netherlands engaged in secret discussions for the joint defence of their territories, in the event of a Japanese attack against any of them.<ref name=USAWWIIcp4>{{cite web |title=The Showdown With Japan Aug–Dec 1941 |website=US Army in WWII – Strategic Planning for Coalition Warfare |pages=63–96 |url=https://www.ibiblio.org/hyperwar/USA/USA-WD-Strategic1/USA-WD-Strategic1-4.html |access-date=15 May 2013 |archive-url=https://web.archive.org/web/20121109144920/https://www.ibiblio.org/hyperwar/USA/USA-WD-Strategic1/USA-WD-Strategic1-4.html |archive-date=9 November 2012 |url-status=live}}</ref> Roosevelt reinforced [[Commonwealth of the Philippines|the Philippines (an American protectorate scheduled for independence in 1946)]] and warned Japan that the United States would react to Japanese attacks against any "neighboring countries".{{r|USAWWIIcp4}}

[[File:The USS Arizona (BB-39) burning after the Japanese attack on Pearl Harbor - NARA 195617 - Edit.jpg|thumb|right|The {{USS|Arizona|BB-39|6}} was a total loss in the [[Attack on Pearl Harbor|Japanese surprise air attack]] on the [[United States Pacific Fleet|American Pacific Fleet]] at [[Pearl Harbor]], Sunday 7 December 1941.]]
Frustrated at the lack of progress and feeling the pinch of the American–British–Dutch sanctions, Japan prepared for war. Emperor [[Hirohito]], after initial hesitation about Japan's chances of victory,<ref>{{cite book|last = Bix  | first = Herbert P.| author-link = Herbert P. Bix | date = 3 November 2016 | title = Hirohito and the making of modern Japan | publisher = HarperPerennial | isbn = 978-0-06-256051-3 | pages = 399–414}}</ref> began to favour Japan's entry into the war.<ref>{{cite journal |url=https://www.asahi.com/ajw/articles/14496398 |journal=The Asahi Shimbun |first=Ryuichi |last=Kitano |title=Diary: Hirohito prepared for U.S. war before Pearl Harbor attack |date=6 December 2021 |access-date=8 June 2022 |archive-date=17 April 2022 |archive-url=https://web.archive.org/web/20220417192302/https://www.asahi.com/ajw/articles/14496398 |url-status=live }}</ref> As a result, Prime Minister [[Fumimaro Konoe]] resigned.<ref>{{cite book | last = Fujiwara | first = Akira | date = 1991 | title = Shōwa tennō no jūgo-nen sensō | page = 126, citing Kenji Tomita's diary}}</ref><ref>Bix, ''Hirohito and the Making of Modern Japan'', pp. 417–420</ref> Hirohito refused the recommendation to appoint [[Prince Naruhiko Higashikuni]] in his place, choosing War Minister [[Hideki Tojo]] instead.<ref>Bix, ''Hirohito and the Making of Modern Japan'', p. 418</ref> On 3 November, Nagano explained in detail the plan of the [[attack on Pearl Harbor]] to the Emperor.<ref>{{cite book | last = Wetzler | first = Peter | date = 1998 | title = Hirohito and War: Imperial Tradition and Military Decision Making in Prewar Japan | publisher = University of Hawai'i Press | isbn = 978-0-8248-1925-5 | pages = 29, 35 | url = https://books.google.com/books?id=BWqEkwH1KRMC&pg=PA29 | access-date = 15 January 2024 | archive-date = 15 March 2024 | archive-url = https://web.archive.org/web/20240315182053/https://books.google.com/books?id=BWqEkwH1KRMC&pg=PA29 | url-status = live }}</ref> On 5 November, Hirohito approved in imperial conference the operations plan for the war.<ref>Bix, ''Hirohito and the Making of Modern Japan'', p. 424</ref> On 20 November, the new government presented an interim proposal as its final offer. It called for the end of American aid to China and for lifting the embargo on the supply of oil and other resources to Japan. In exchange, Japan promised not to launch any attacks in Southeast Asia and to withdraw its forces from southern Indochina.{{r|USAWWIIcp5}} The American counter-proposal of 26 November required that Japan evacuate all of China without conditions and conclude non-aggression pacts with all Pacific powers.<ref>[https://www.ibiblio.org/pha/pha/congress/app-d.html#363 The United States Replies] {{Webarchive|url=https://web.archive.org/web/20130429222741/https://www.ibiblio.org/pha/pha/congress/app-d.html#363 |date=29 April 2013 }}. Investigation of the Pearl Harbor attack.</ref> That meant Japan was essentially forced to choose between abandoning its ambitions in China, or seizing the natural resources it needed in the Dutch East Indies by force;<ref>{{Harvnb|Painter|2012|p=26}}: "The United States cut off oil exports to Japan in the summer of 1941, forcing Japanese leaders to choose between going to war to seize the oil fields of the Netherlands East Indies or giving in to U.S. pressure."</ref><ref>{{Harvnb|Wood|2007|p=9}}, listing various military and diplomatic developments, observes that "the threat to Japan was not purely economic."</ref> the Japanese military did not consider the former an option, and many officers considered the oil embargo an unspoken declaration of war.{{sfn|Lightbody|2004|p=125}}

Japan planned to seize European colonies in Asia to create a large defensive perimeter stretching into the Central Pacific. The Japanese would then be free to exploit the resources of Southeast Asia while exhausting the over-stretched Allies by fighting a defensive war.<ref>{{Harvnb|Weinberg|2005|p=310}}</ref><ref>{{Harvnb|Dower|1986|p=5}}, calls attention to the fact that "the Allied struggle against Japan exposed the racist underpinnings of the European and American colonial structure. Japan did not invade independent countries in southern Asia. It invaded colonial outposts which the Westerners had dominated for generations, taking absolutely for granted their racial and cultural superiority over their Asian subjects." Dower goes on to note that, before the horrors of Japanese occupation made themselves felt, many Asians responded favourably to the victories of the Imperial Japanese forces.</ref> To prevent American intervention while securing the perimeter, it was further planned to neutralise the [[United States Pacific Fleet]] and the American military presence in the Philippines from the outset.{{sfn|Wood|2007|pp=11–12}} On 7 December 1941 (8 December in Asian time zones), Japan attacked British and American holdings with near-simultaneous [[Japanese expansion (1941–42)|offensives against Southeast Asia and the Central Pacific]].{{sfn|Wohlstetter|1962|pp=341–343}} These included an [[Attack on Pearl Harbor|attack on the American fleets at Pearl Harbor]] and [[Philippines campaign (1941–1942)|the Philippines]], as well as invasions of [[Battle of Guam (1941)|Guam]], [[Battle of Wake Island|Wake Island]], [[Malayan campaign|Malaya]],{{sfn|Wohlstetter|1962|pp=341–343}} [[Japanese invasion of Thailand|Thailand]], and [[Battle of Hong Kong|Hong Kong]].<ref>[[John Keegan|Keegan, John]] (1989) ''The Second World War''. New York: Viking. pp. 256–257. {{isbn|978-0399504341}}</ref>

These attacks led the [[United States declaration of war on Japan|United States]], [[United Kingdom declaration of war on Japan|United Kingdom]], China, Australia, and several other states to formally declare war on Japan, whereas the Soviet Union, being heavily involved in large-scale hostilities with European Axis countries, maintained its neutrality agreement with Japan.<ref>{{Harvnb|Dunn|1998|p=157}}. According to {{Harvnb|May|1955|p=155}}, Churchill stated: "Russian declaration of war on Japan would be greatly to our advantage, provided, but only provided, that Russians are confident that will not impair their Western Front."</ref> Germany, followed by the other Axis states, declared war on the United States<ref>[[s:Adolf Hitler's Declaration of War against the United States|Adolf Hitler's Declaration of War against the United States]] in Wikisource.</ref> in solidarity with Japan, citing as justification the American attacks on German war vessels that had been ordered by Roosevelt.{{r|Events1941}}<ref>{{citation |last1=Klooz |first1=Marle |last2=Wiley |first2=Evelyn |others=Director: Humphrey, Richard A. |year=1944 |title=Events leading up to World War II – Chronological History |series=78th Congress, 2d Session – House Document N. 541 |location=Washington, DC |publisher=US Government Printing Office |at=p. 310 ([https://www.ibiblio.org/pha/events/1941.html 1941]) |url=https://www.ibiblio.org/pha/events/ |access-date=9 May 2013 |archive-url=https://web.archive.org/web/20131214113907/https://www.ibiblio.org/pha/events/ |archive-date=14 December 2013 |url-status=live}}</ref>