After having become an expert on the incident from having skimmed half of the wikipedia article, I note that it mentions both Reagan considering his letter an apology and the US government not having made a formal apology, so I imagine there is some clever political distinction between the two.
I guess because they think it doesn't benefit them and will make future diplomacy harder? I don't know if that falls under arrogance, but I also don't know how to ascribe comprehensible motivations to the state department or whoever is in charge of that.
Treasury Secretary Robert E. Rubin and Vietnamese Finance Minister Nguyen Sinh Hung agreed today that Vietnam will repay the United States approximately $145 million in economic debts owed by the former Republic of Vietnam.
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