depends on if you truly live in US

If you are "really" living in US, live a boring life of going to work every day, as a resident alien, your taxable estate is exempted for $5.25 mil, no matter who is in line for inheritance.  You only pay estate tax for properties more than 5.25 mil. 

If you are flying around the world and stays abroad for a long time, you might be deemed non-resident owning US property (e.g. Saudi prince, Russian oligarch owing NYC loft), your taxable estate is exempted for only $60K.  Anything beyond $60K is subject to estate tax.  

If in doubt, you should consult a estate lawyer.