The Moscow-backed Yanukovych said Russia is Ukraine's main partner in the defense sector. He ordered his deputy to launch talks immediately with Moscow.
The announcement could hurt Ukraine's bid to join NATO.
Ukraine's pro-Western President, Viktor Yushchenko, has made NATO membership a key goal for Ukraine.
RFE/RL Belarus, Ukraine, And Moldova Report
SUBSCRIBE For weekly news and analysis on Belarus, Ukraine, and Moldova by e-mail, subscribe to "RFE/RL Belarus, Ukraine, And Moldova Report."