Of recent wars (1900 to today) I can only think of instances of the U.S. sending offensive troops to occupy other nations.

I understand that we've been attacked by the likes of Pearl Harbor and 9/11 but when was the most recent time that a foreign power had military occupancy on the U.S.'s soil/waters?

My research has led me to Wikipedia's list of military occupations but I am uncertain whether or not Guam counts and the list doesn't go back very far.

  • Do covert visits count? – Aaron Brick Dec 11 '18 at 18:29
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    If you don't count the Civil War, then during the War of 1812. Though technically (since embassies are considered to be the country's territory), the 1979 occupation of the US embassy by Iran could count. – jamesqf Dec 11 '18 at 18:34
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    Only you can answer if Guam and the Aleutian Islands count - it is your question. How do you define "U.S." in this context? States only? Or Territories as well? If States Only, that should be specified in the Q - same if Territories should be included. (Oh - and whether or not the one and only District counts too). – Kerry L Dec 11 '18 at 18:55
  • @KerryL I am not a history buff nor am I asking this as a homework question. Do you think they should count? Does the occupation of territories provide strategic advantage for the foreign power? Did the U.S. have to engage with the invaders in order to make them leave? – MonkeyZeus Dec 11 '18 at 19:50
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    I'm not sure this exactly answers the question, but the US and Canada are still involved in border disputes, mainly over sea areas but also a few islands. There are particularly fierce disagreements over land and water between Maine (US) and New Brunswick (Canada). Machias Seal Island is claimed by the US but is currently occupied by Canada which has a manned lighthouse there (not troops), and fisheries protection vessels patrol the sea. macleans.ca/news/canada/… – Stuart F Dec 12 '18 at 12:19

Oops! You changed the title of the question.

I originally answered that according to the original title of your question that never happened.

To answer the title of your question, never.

The phrase "The U.S. was occupied by foreign troops" means that the entire United States of America was occupied by foreign troops, not that some tiny part of the USA was occupied by foreign troops. Since the official independence of the USA in 1783 there has never been a single moment when the entire USA was occupied by foreign troops.

But I also answered the text of your question:

But if "when was the most recent time that a foreign power had military occupancy on the U.S.'s soil/waters?" asks about foreign military occupation of parts, however large or small, of the USA instead of the entire USA then there have been several times in history when that has happened.

I think that the latest time there has been any foreign military occupation of any part of the USA would have been during World War Two in 1941-1945, when Japan occupied for varying lengths of time several regions that were part of the USA.

For example, Japan invaded the Philippines on 8 December 1941 a few hours after the attack on Pearl Harbor and completed the conquest on 6 May 1942. The US lead invasion force landed in the Philippines on 20 October 1944 and fighting continued until the Japanese surrender on 2 September 1945. So if the Philippines are considered to be "U.S.'s soil/waters" 2 September 1945 would be the answer.


Japanese forces invaded and occupied Attu and Kiska, two of the Aleutian Islands in the Territory, and later State, of Alaska on Junes 3, 1942, and the last Japanese troops didn't retreat from Kiska until July 29, 1943.


So the last time that any part of the USA was occupied by foreign troops would probably be either 29 July 1943 or 2 September 1945, depending on whether the Philippine Islands are considered to be part of the USA during 1941-1945.

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    Your answer is still valid and I appreciate it. I felt the need to change the title due to a barrage of comments asking for clarifications which have since been deleted. – MonkeyZeus Dec 11 '18 at 19:09
  • If you're going to be pedantic, the entire United States has never been occupied by anyone, including Americans :-) – jamesqf Dec 12 '18 at 19:13
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    @MAGolding, a nit perhaps but the Philippines was not part of the United States in the 1940's but had their own civilian government. In 1935, the Commonwealth of the Philippines was established with U.S. approval, and Manuel Quezon was elected the country’s first president. To your point, they didn't gain full independence until after WWII in 1946. – JMS Dec 13 '18 at 19:51

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