US citizens serving in an allied foreign military

Reading a Snopes article about the deaths on D-Day compared to the number of Americans killed this year by firearms, it mentioned that a couple of US citizens died while serving in the Canadian army.

I’ve also heard that Americans have sometimes served in the military of other allied nations (the RAF was one, IIRC) when there was a war in Europe but before the US entered it.

Is that (or was it at the time) perfectly legal, or might it be grounds for arrest or even cost someone their citizenship? Did the US have an agreement with those other nations? Is anybody doing that today?

I suppose some of them could have been dual-citizens, but that leads to more questions. If someone is a citizen of two allied countries, and he is drafted by both nations, how do they sort it out?

My uncle seeking adventure and glory (and running from a horrific mother) left California and made his way to Canada to join the Royal Canadian Air Force. He never left Canada and when the US entered the war he deserted and came back over and joined the US Navy. He always joked he would be arrested if he every went in to Canada. I have no idea if he tried. He never had to become a Canadian citizen. Things were a lot looser then.

SFAIK it’s against US law for a US citizen to join the armed forces of a foreign country (whether allied to the US or not) while still in the United States. But if you go to Umbrellastan and enlist in the Umbrellastani forces there, that’s not an offence (unless Umbrellastan is in conflict with the US, of course).

If you join a foreign countries forces with the intention of US citizenship, then your US citizenship is of course at risk. So it might be wise to scrutinise carefully the exact terms of any oath of allegiance or similar that you will make on joining the Umbrellastani forces.

Partially indicative - as a dual citizen, US and Australia, I could be enlist in either military, so long as I did not become a commissioned officer*. Enlisted man, NCO, both okay, but if I accepted a commission I’d have to renounce one or the other citizenship. Being a commissioned officer shows “overriding faith and allegiance” to that particular country, if I remember the phrasing correctly.
From this, I would guess that enlisting in a non-hostile military as a non-citizen is just hunky-dory; especially in wartime, when everyone is too busy to worry about such things.
So far as the draft goes…I don’t know. Neither country currently has the draft, and I’m too old anyway. According to the Wiki article on multiple citizenship:

Which strikes me as the common-sense solution to a fairly rare case.

I’ll note that different countries have different ways of dealing with multiple citizenship, so consult a lawyer if you’re actually stuck in some weird situation!

At the start of WW2, many American pilots joined the Allies that were already fighting.

I’ve known several dual Israeli-U.S. citizens - including my own brother - who served as commissioned officers in the Israeli army, and no-one ever gave them any trouble with it.

At least at one time, American citizens could and did serve in Israeli reserves and when called up had to jump on the next available plane to Israel. I could be wrong but some of those people were not actually Israeli citizens-they were solely US citizens but had family or historical roots in Israel. And I believe this was allowed by a special US law. But again, I am going on old memories.

Is Israel formally militarily allied with the US? Why would they need a special law? What’s to prevent a US citizen from joining the French Foreign Legion? And would they care, beyond security clearance issues, if someone was, let’s say, a major in the Iranian or Russian or other non-allied military?

In fact, a small number of American citizens served in the German armed forces during World War 2. After the war, they were generally allowed to keep their U.S. citizenship, iirc. I imagine, in theory, they could have been prosecuted, but I guess it was decided that it wasn’t worth the trouble.

More than a few African American Soldiers fought in the French Army and Air Force during WWI.

My best friend, an American citizen, joined the Canadian Forces in 1987, and in fact he was not a Canadian citizen at the time; he became one three years later (while still in the Forces.) Nothing bad happened, and he had a letter from the State Department saying he was okay, and in 1999 moved back to the USA.

I can’t answer for Australia but you would not lose your US citizenship after the Afroyim v. Rusk decision in 1967.

If you renounced your citizenship to take the commission, you could.

I’ve heard that nowadays you don’t lose your U.S. citizenship except under pretty extreme circumstances, and that you are for the most part perfectly fine serving in a foreign military, as long as it’s a US-friendly nation like Denmark or Ireland. Joining an adversary like Iran or North Korea, though, would put you in serious jeopardy.

Copy pasting US code. (Indenting is a problem.)

"8 U.S. Code § 1481. Loss of nationality by native-born or naturalized citizen; voluntary action; burden of proof; presumptions.

(a) A person who is a national of the United States whether by birth or naturalization, shall lose his nationality by voluntarily performing any of the following acts with the intention of relinquishing United States nationality—

(2) taking an oath or making an affirmation or other formal declaration of allegiance to a foreign state or a political subdivision thereof, after having attained the age of eighteen years; or
(3) entering, or serving in, the armed forces of a foreign state if (A) such armed forces are engaged in hostilities against the United States, or (B) such persons serve as a commissioned or non-commissioned officer; or

(7) committing any act of treason against, or attempting by force to overthrow, or bearing arms against, the United States, violating or conspiring to violate any of the provisions of section 2383 of title 18, or willfully performing any act in violation of section 2385 of title 18, or violating section 2384 of title 18 by engaging in a conspiracy to overthrow, put down, or to destroy by force the Government of the United States, or to levy war against them, if and when he is convicted thereof by a court martial or by a court of competent jurisdiction."

It’s routine for people in certain positions, e.g., pilots to be an officer. And it is quite limiting to not ever become an NCO.

I think the US generally looks the other way on such matters unless you are a real jerk.

The US and Israel are “Major Strategic Partners,” but there is no formal alliance between the two nations. The US’ formal alliances are NATO, ANZUS, the Rio Pact and the OAS, along with individual formal alliances with Japan, the Republic of Korea, the Phillipines and Morocco. The strength of these alliances vary, of course: the OAS is a much looser agreement than NATO, of course.

While there’s nothing to prevent a US national from joining a foreign nation’s military, the US can determine that by doing so, you’ve relinquished your citizenship, particularly if that military is hostile to the US. The determination of what is considered hostile is not up to the citizen/soldier, but to the US State Department. The law says that you lose your US citizenship only if you intended to do so when joining the foreign military, continuing to serve when engaged in hostile acts against the US, or by becoming an officer or NCO. Apparently the State Department intentionally turns a blind eye to the third part, and takes a very broad view of the second.

Gibbon observed that it became easy to acquire Roman citizenship at the same time that it ceased to have any value. I think that something of the same sort is happening to American citizenship now.

Not at all I know plenty of people who would love to live in America but can’t get a green card.

When I was a boy it was easy to loose American citizenship. Now it’s difficult. That has changed.

That may or may not be true but that has nothing do with your original statement which was discussing how easy has become to acquire American citizenship. Quite frankly, it ain’t.

Even if it is true, that doesn’t necessarily support your conclusion which is that American citizenship is becoming less valued.

That’s absurd and I just pointed out one reason.

Also, comparing anything to the fall of Rome ought to be its own logical fallacy. That old comparison is the sign of a lazy argument when writers have nothing else.