I read it as this.
Ukraine was actively seeking membership with Nato. They had agreements in effect with Nato but to become a full member they had to make several reformations in their government towards democracy.
They were cooperating with Nato on the transformations necessary.
They would never be able to join Nato if Russia took complete control of them. Russia has stated they don't want the Ukraine to join Nato EVEN THOUGH the agreements that Russia has signed with Nato prohibits them from making a decision like that.
More quotes from NATO:
According to Article I of the Helsinki Final Act (here) which established the Organisation for Security and Cooperation in Europe (OSCE) in 1975, every country has the right "to belong or not to belong to international organizations, to be or not to be a party to bilateral or multilateral treaties including the right to be or not to be a party to treaties of alliance." All the OSCE member states, including Russia, have sworn to uphold those principles.
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NATO has responded to the new strategic reality caused by Russia's illegitimate and illegal actions in Ukraine by reinforcing the defence of Allies in Central and Eastern Europe, and by ensuring the ability to increase those reinforcements if necessary, including by upgrading infrastructure.
All this is consistent with the Founding Act, quoted above.
In the Founding Act, all signatories, including Russia, agreed on principles which include "refraining from the threat or use of force against each other as well as against any other state, its sovereignty, territorial integrity or political independence in any manner inconsistent with the United Nations Charter and with the Declaration of Principles Guiding Relations Between Participating States contained in the Helsinki Final Act" and the "respect for sovereignty, independence and territorial integrity of all states and their inherent right to choose the means to ensure their own security, the inviolability of borders and peoples' right of self-determination as enshrined in the Helsinki Final Act and other OSCE documents."
NATO has respected those commitments faithfully. Russia, on the other hand, has declared the annexation of Crimea, supported violent separatists in the east of the country, and insisted that Ukraine be barred from joining NATO.