Question details
I am working in a Federal Gov't Agency, and in the near future leaving for Frankfurt, Germany, for a conference, and with a plan in mind to fly to USA via Germany after my conference is completed. My question, here, is that whether I can use my US visa, which is valid up to Apr 06/2012, whereas the passport has already expired by last May 23/2011, and due to be replaced by a new one.
ANSWER
You will need an unexpired passport to enter USA. People in your situation carry both the new and the old passports.