premise: In 1997, Russia and Ukraine signed the Partition Treaty, establishing two independent national fleets and dividing armaments and bases between them. Ukraine also agreed to lease major parts of its facilities to the Russian Black Sea Fleet until 2017. However, the treaty appeared to be far from perfect: permanent tensions on the lease details  control continued. The Fleet's main base is still situated in the Crimean port city of Sevastopol. In 2009 the Yushchenko Ukrainian government declared that the lease would not be extended and that the fleet would have to leave Sevastopol by 2017.  In 2010 the Russian leasehold was renegotiated with an extension until 2042 and an option for an additional five years until 2047.
hypothesis: for 23 years from the original deadline was the lease extended