Ukraine planned an audacious attack on Moscow to mark the first anniversary of Russia's invasion.
Kyrylo Budanov had plans to attack Moscow
The attack was ultimately called off after an intervention from the United States that warned Kyiv that it could spark World War III.
The plans for the February 24 attack on Moscow by Ukraine's HUR military intelligence were revealed in leaked spy documents seen by the Washington Post newspaper.
Intelligence boss Major General Kyrylo Budanov instructed his officers to prepare for "mass strikes", the National Security Agency documents have revealed.
As well as attacking Moscow, the Ukrainians also considered hitting the Black Sea port of Novorossiysk.
However, officials in Washington seemed to have discovered the plans and became worried that the strikes could spark a wider military conflict.
Initial attempts to persuade Kyiv appeared to be unsuccessful but two days before the attack the CIA said that HUR "had agreed, at Washington's request, to postpone strikes".
While Ukraine ultimately held off from an attack on Russia on the anniversary, a Russian airbase was rocked by massive explosions following a suspected drone strike shortly after the milestone day.
The spy documents indicate that US intelligence has been eavesdropping on Budanov's communications and reveal tensions between Kyiv and Washington over the extent to which American weapons can be used to carry the war into Russia itself.