As we wrote earlier, TOSFOS in Nazir (54b, DH Eretz ha'Amim) writes that the decree of Tum'ah on the land of the gentiles was (1) because of the large number of Jews that were killed in Chutz la'Aretz, or (2) because of the gentiles who died before the Torah was given, whose corpses indeed are Metamei (as Tosfos writes there in Nazir 54a, DH O b'Kever), or (3) perhaps the Rabanan were stringent regarding the airspace of the land of the gentiles so that Jews would not leave Israel to go Chutz la'Aretz.

However, according to all of these reasons, the Tum'ah is only a Rabbinic enactment. The Rabanan decreed Tum'ah on the land of Chutz l'Aretz for one of the above reasons, with regard to Terumah. They did not enact that a Kohen may not go there. Therefore the original Torah ruling remains true as far as Kohanim are concerned, and Chutz l'Aretz is still Tahor.

Yours, Mordecai

(PS - Check the date on your computer, I think your date is wrong, causing me to almost miss your letter. Be well, MK)