[mikeIII]

It seems she lied to US banks, as a result of which the banks cooperated with Huawei in violating US sanctions. Still, how this gives us legal right to have someone arrested outside the US, I don’t understand. I’d hate to see Americans subjected to similar actions abroad!

[mrsmith]

I think Americans should be prosecuted for bank fraud by any country with a functioning legal system.

[Svartalfiar]

Still, how this gives us legal right to have someone arrested outside the US, I don’t understand. I’d hate to see Americans subjected to similar actions abroad!

Because countries agree to help arrest each other's criminals. It's why criminals don't just run away to some other country to escape prosecution.

And, Americans aren't only subjected to similar action abroad, you're subject to that same thing right here at home! Even WITHOUT an extradition treaty:

18 U.S. Code § 3196 - Extradition of United States citizens

If the applicable treaty or convention does not obligate the United States to extradite its citizens to a foreign country, the Secretary of State may, nevertheless, order the surrender to that country of a United States citizen whose extradition has been requested by that country if the other requirements of that treaty or convention are met.
(Added Pub. L. 101–623, § 11(a), Nov. 21, 1990, 104 Stat. 3356.)