Harvey and Lee vs. Richard Case Nagell

[Greg Burnham]

[snip]

Khrushchev is said to have annulled the plan, but Soviet agents were unable to reach Oswald before Khrushchev's annulment order could be executed.

I don't know who you are quoting there, David, but that is not what Pacepa asserts. Unless, the phrase "reach Oswald" in this context means "find and terminate Oswald".
The author contends not that Oswald was unaware of the abort order, but rather, that he chose to ignore the abort order. Therefore, if we are to believe this fanciful tale
it means that Khrushchev originally had ordered a hit on JFK, but due to his hand having been exposed in similar wet operation activities, he decided to abort the plan.
The abort order was successfully transmitted to Oswald, but Oswald chose to ignore it. The only recourse from Moscow would have been to "get to Oswald" before he could
complete the mission and prevent him from executing it by taking him out. Which begs us to ask: If Ruby was a Zionist, formerly NKVD, with current ties to Moscow, was he
remiss in his duties by having failed to prevent Oswald from killing Kennedy, which would explain his anxiety leading up to his finally fulfilling his mission albeit after-the-fact?
Ruby's belated action would indeed have prevented Oswald from implicating Moscow in a court room. But, would there be a benefit to Zionism in the exchange? IOW: Did Ruby
fail to prevent the assassination in order to thwart KGB, but succeed in silencing Oswald after the fact in order to serve Zionistic interests?