However this "thaw" was short lived. Khrushchev got into power and had to beat the Eastern Block into shape, they formed the Warsaw Pact in '55, which signaled a serious military opposition of the West. Not that Nagy's goverment headed there, but Moscow felt serious doubts towards them. One of the reason was that the Rákosi and Co - with their wounded ego - were whispering into their ears, trying to taint Nagy. And because they considered producing food as a dangerous imperialist deviation.
So in 1955 Nagy was called to Moscow and it was his turn to practice self-criticism. He refused. He tried to justify the New Course. He was
replaced as PM by Hegedűs András, who was a faithful Rákosist, and previously directed the collectivization of the land and the misguided agriculture policy. His trustworthiness is demonstrated by the fact that he was called to Moscow as well, to promote him, and he was the PM who signed our accession into the Warsaw Pact. He remained the PM until the revolution removed him, and reinstated Nagy.