If a married person living in Hutz La’aretz (outside Eretz Yisrael) spends Yom Tob in Israel, and plans to return to his home in Hutz La’aretz afterward, then he must observe two days of Yom Tob despite being in Israel. Although people who live in Israel observe only one day, a person who visits Israel temporarily retains his status as a Diaspora resident, and must therefore observe two days of Yom Tob. This means that even on the second day, he recites Kiddush (with Shehehiyanu) and the Yom Tob prayers, does not wear Tefillin, and so on. He treats the second day as a full-fledged Yom Tob as though he were in Hutz La’aretz, both for matters involving stringency (like Melacha, Kiddush and so on) and for those involving leniency (like not wearing Tefillin).

An interesting question arises in a case of a visitor to Israel who happens to be an expert Mohel, and he is invited to perform a Berit Mila for an Israeli infant on the second day of Yom Tob. Is he allowed to perform the Berit, in light of the fact that Misva of Berit Mila (when performed on an infant’s eighth day) overrides the Shabbat and Yom Tob restrictions? Or, must the family bring an Israeli Mohel, for whom that day is a weekday, rather than force this visitor to violate Yom Tob by performing the circumcision?

Hacham Ovadia Yosef, in Hazon Ovadia (p. 154), rules that the Mohel may perform the Berit Mila in such a case, and there is no need for the parents to choose an Israeli Mohel who is not observing Yom Tob that day. Since Berit Mila for an eight-day-old boy is permitted on Shabbat and Yom Tob, a Mohel observing Yom Tob does not desecrate Yom Tob at all by performing the Berit Mila, and it is entirely permissible for him to perform the circumcision. Hacham Ovadia’s ruling is also cited in Yalkut Yosef (listen to audio recording for precise citation).

Summary: If a Mohel is visiting Israel for Yom Tob, he may be invited to perform a Berit on the second day of Yom Tob for an eight-day-old baby, and the parents do not have to bring an Israeli Mohel, who is not observing Yom Tob that day.