Tax liability on overseas property sales when proceeds are kept overseas.

A U.S. citizen or resident must report worldwide income. Report property sale on schedule D (Form 1040).
If you paid taxes in the foreign country, you will claim credit for taxes paid in the foreign country by filing Form 1116.
Another filing requirement is Form TD F 90-22.1. Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income