Ph.D Transfer from other country to US In this application cycle, I got a PhD offer from Nanyang Technology University at Singapore and will study in the field of programming language. However, I recently received a mail from my supervisor which is said that he will soon leave NTU for some reasons. After searching the faculty list of NTU I found there is no other professor who works in programming language. 

I don't want to compromise on the topic I will do during my PhD. Maybe it is a good choice for me to find a matching supervisor in some other universities.
But I have to go to NTU to do my PhD because I have no alternative choice now since this application cycle is ended.

What I want to know is that is it possible to transfer my PhD from singapore to US if I re-apply for some American universities after my current supervisor's leave?

Any advise will be so much appreciate for that I somehow don't know what to do.
In general, it is difficult to transfer between universities in different countries unless one is moving with the thesis advisor. This is in part because of funding rules: usually, money in one country cannot be used to fund graduate students working or studying in another country. (In the US, for instance, graduate fellowships are normally valid only at US universities.)

If you were to attempt to transfer on your own, the most likely scenario is that you would be expected to start the PhD over; depending on the department, they may not recognize coursework completed at your old school, or at best may choose to give you placement out of the equivalent courses, but still expect you to complete additional electives. It would be even more challenging to move your project over, if funding isn't available to work on the same project.

Since you are just starting, perhaps it would be possible to complete a master's degree in Singapore, and then try to transfer to another university for the doctoral studies. (I'm not sure how doctoral programs in CS handle an international master's. In my department, though, students with master's from abroad were still expected to complete the "core" coursework requirements.)