It started earlier when Russia violated the Budapest Memorandum.
It started earlier when Russia violated the Budapest Memorandum.
Specifically, the Budapest Memorandum of 5 December 1994 provided:
4. The Russian Federation, the United Kingdom of Great Britain and Northern Ireland, and the United States of America reaffirm their commitment to seek immediate United Nations Security Council action to provide assistance to Ukraine, as a non-nuclear-weapon state party to the Treaty on the NonProliferation of Nuclear Weapons, if Ukraine should become a victim of an act of aggression or an object of a threat of aggression in which nuclear weapons are used.
Ukraine was assured that UN Security Council consideration would be sought.
The matter was, in fact, referred to the UN Security Council where a motion to take action against Russia failed. And with that, the total assurance of the Memorandum was complied with.
Ukraine and Russian Federation
Entry into force: 1 April 1999, in accordance with article 39
Article 6Each High Contracting Party shall refrain from participating in, or supporting, any actions directed against the other High Contracting Party, and shall not conclude any treaties with third countries against the other Party. Neither Party shall allow its territory to be used to the detriment of the security of the other Party.