28 to Zero

As taken from this page:

there have been 28 cases (some of them spanning multiple years) of US forces involved in military operations on Chinese soil. Unless I’m mistaken, that compares to exactly zero the other way around.

1843 – China. Sailors and marines from the St. Louis were landed after a clash between Americans and Chinese at the trading post in Canton.[RL30172]

1854 – China. April 4 to June 15 to 17. American and English ships landed forces to protect American interests in and near Shanghai during Chinese civil strife.[RL30172]

1855 – China. May 19 to 21. U.S. forces protected American interests in Shanghai and, from August 3 to 5 fought pirates near Hong Kong.[RL30172]

1856 – China. October 22 to December 6. U.S. forces landed to protect American interests at Canton during hostilities between the British and the Chinese, and to avenge an assault upon an unarmed boat displaying the United States flag.[RL30172]

1859 – China. July 31 to August 2. A naval force landed to protect American interests in Shanghai.[RL30172]

1866 – China. June 20 to July 7. US forces punished an assault on the American consul at Newchwang.[RL30172]

1894–95 – China. Marines were stationed at Tientsin and penetrated to Peking for protection purposes during the First Sino-Japanese War.[RL30172]

1894–95 – China. A naval vessel was beached and used as a fort at Newchwang for protection of American nationals.[RL30172]

1898–99 – China. November 5, 1898 to March 15, 1899. US forces provided a guard for the legation at Peking and the consulate at Tientsin during contest between the Dowager Empress and her son.[RL30172]

1900 – China. May 24 to September 28. Boxer Rebellion American troops participated in operations to protect foreign lives during the Boxer uprising, particularly at Peking. For many years after this experience a permanent legation guard was maintained in Peking, and was strengthened at times as trouble threatened.[RL30172]

1911 – China. As the Tongmenghui-led Xinhai Revolution approached, in October an ensign and 10 men tried to enter Wuchang to rescue missionaries but retired on being warned away, and a small landing force guarded American private property and consulate at Hankow. Marines were deployed in November to guard the cable stations at Shanghai; landing forces were sent for protection in Nanking, Chinkiang, Taku and elsewhere.[RL30172]

1912 – China. August 24 to 26, on Kentucky Island, and August 26 to 30 at Camp Nicholson. US forces protected Americans and American interests during the Xinhai Revolution.[RL30172]

1912–41 – China. The disorders which began with the overthrow of the dynasty during Kuomintang rebellion in 1912, which were redirected by the invasion of China by Japan, led to demonstrations and landing parties for the protection of US interests in China continuously and at many points from 1912 on to 1941. The guard at Peking and along the route to the sea was maintained until 1941. In 1927, the United States had 5,670 troops ashore in China and 44 naval vessels in its waters. In 1933 the United States had 3,027 armed men ashore. The protective action was generally based on treaties with China concluded from 1858 to 1901.[RL30172]

1916 – China. American forces landed to quell a riot taking place on American property in Nanking.[RL30172]

1917 – China. American troops were landed at Chungking to protect American lives during a political crisis.[RL30172]

1920 – China. March 14. A landing force was sent ashore for a few hours to protect lives during a disturbance at Kiukiang.[RL30172]

1922–23 – China. April 1922 to November 1923. Marines were landed five times to protect Americans during periods of unrest.[RL30172]

1924 – China. – September. Marines were landed to protect Americans and other foreigners in Shanghai during Chinese factional hostilities.[RL30172]

1925 – China. January 15 to August 29. Fighting of Chinese factions accompanied by riots and demonstrations in Shanghai brought the landing of American forces to protect lives and property in the International Settlement.[RL30172]

1926 – China. August and September. The Nationalist attack on Hankow brought the landing of American naval forces to protect American citizens. A small guard was maintained at the consulate general even after September 16, when the rest of the forces were withdrawn. Likewise, when Nationalist forces captured Kiukiang, naval forces were landed for the protection of foreigners November 4 to 6.[RL30172]

1927 – China. February. Fighting at Shanghai caused American naval forces and marines to be increased. In March a naval guard was stationed at American consulate at Nanking after Nationalist forces captured the city. American and British destroyers later used shell fire to protect Americans and other foreigners. Subsequently additional forces of marines and naval forces were stationed in the vicinity of Shanghai and Tientsin.[RL30172]

1932 – China. American forces were landed to protect American interests during the Japanese occupation of Shanghai.[RL30172]

1934 – China. Marines landed at Foochow to protect the American Consulate.[RL30172]

1945 – China. In October 50,000 US Marines were sent to North China to assist Chinese Nationalist authorities in disarming and repatriating the Japanese in China and in controlling ports, railroads, and airfields. This was in addition to approximately 60,000 US forces remaining in China at the end of World War II.[RL30172]

1945–47 – US Marines garrisoned in mainland China to oversee the removal of Soviet and Japanese forces after World War II.[3]

1948–49 – China. Marines were dispatched to Nanking to protect the American Embassy when the city fell to Communist troops, and to Shanghai to aid in the protection and evacuation of Americans.[RL30172]

1950–55 – Formosa (Taiwan). In June 1950 at the beginning of the Korean War, President Truman ordered the US Seventh Fleet to prevent Chinese Communist attacks upon Formosa and Chinese Nationalist operations against mainland China.[RL30172]

1954–55 – China. Naval units evacuated US civilians and military personnel from the Tachen Islands.[RL30172]

This list doesn’t include the following incident hat occurred in 2001:

2001 – On April 1, 2001, a mid-air collision between a United States Navy EP-3E ARIES II signals surveillance aircraft and a People’s Liberation Army Navy (PLAN) J-8II interceptor fighter jet resulted in an international dispute between the United States and the People’s Republic of China called the Hainan Island incident.

I’m curious what the outcome might’ve been if the situation had been reversed and a Chinese surveillance aircraft had been in a similar situation around US territorial waters.