Should he fast with his own country or with any country that sights the new moon?

No File Exists
Check below answers in case you are looking for other related questions:
The Muslims should cooperate in sighting the moon and informing the authorities
It is permissible to use telescopes etc., but not calculations, to sight the new moon

No File Exists
Related Answers:
He travelled during Ramadaan to a country where the people started Ramadaan on a different day
Ruling on fasting and breaking the fast of one whose testimony was rejected or who was not able to inform the authorities
Should he follow the local people with regard to starting and ending the fast?
The Muslims should cooperate in sighting the moon and informing the authorities
It is permissible to use telescopes etc., but not calculations, to sight the new moon

Recommended answers for you:
Differences between semen (maniy) and urethral fluid (madhiy)
Does nail polish invalidate wudoo’ and do the prayers have to be repeated?
Ruling on making up missed prayers
Ruling on using the masbahah (prayer beads)
Dreams