"Syria is handing over chemical weapons under international control because of Russia," Assad told Rossiya 24 state news channel in an interview with its correspondent in Damascus.
"US threats have not affected the decision to hand over chemical arms," Assad was also quoted as saying in a caption on the channel's breaking news ticker.
Assad added in the interview that his country planned to file the relevant documents to the United Nations to sign an agreement on chemical arms.
Russia has said Syria will have to join the Organization for the Prohibition of Chemical Weapons as part of the handover deal, which is to be discussed in talks later Thursday in Geneva between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov.
Rossiya 24 did not give any further details of the content of the interview, which it said would be broadcast in full "soon".