BBC News - North Korea frees detained US men Miller and Bae
Clapper held direct talks with the North Korean authorities to secure the releases.
The BBC's Charles Scanlon says that the contact will lead to hope of a breakthrough in the long diplomatic deadlock between the two sides.
The US department of state said in a statement that it "welcomes the release of US citizens Kenneth Bae and Matthew Todd Miller from the DPRK [North Korea], where they have been held for two years and seven months, respectively".
It added: "The United States has long called on DPRK authorities to release these individuals on humanitarian grounds. We join their families and friends in welcoming them home."