"I am pursuing the policy toward integration without adding anything else," Viktor Yushchenko said during a ceremony to sign the document.
Yushchenko has made accession to NATO a priority since coming to power on the back of the 2004 "orange revolution," but prime-ministerial nominee Viktor Yanukovych, the leader of the country's main pro-Russia party, has opposed the move.
"There are fundamental things, such as Ukraine's law on national security, that outline cooperation with NATO, including membership, which was supported by the majority in parliament," Yushchenko said.
Under the terms of the national unity pact, which has been signed by all main political forces except the Yulia Tymoshenko Bloc, the decision on Ukraine's integration into the military bloc will be made following a referendum to be held after Ukraine implements all the necessary procedures.
