RFE/RL has been experiencing a distributed denial-of-service (DDoS) attack intermittently since December 8.
RFE/RL said on December 10 it is working to block further disruption to its operations, and every effort is being made to maintain access to programs online and on the air.
RFE/RL President and CEO Kevin Klose said, "We are reporting this attack now in response to the needs of our audiences, who rely on RFE/RL reporting."
He added: "We deeply regret the inconvenience presented by this attack, which we believe may be targeted, and appeal to our audiences to stay with us and not be deterred."
RFE/RL experienced a similar DDoS attack last month.
A DDoS attack targeted RFE/RL's Belarus Service in 2008.