I can only speak about Kennan - basically his reports and telegrams from his time in Moscow convinced the US government that the USSR was expansionist and a danger to the US.

His reports were the primary driving force that led the US to have a negative attitude towards the USSR and that they needed to contain it. That basically kicked off the cold war and we continue to feel the effects of until today.

He then eventually changed his mind and became very vocal against US foreign policy towards the USSR (basically the same policies that he recommended).

Edited: a word

George Albert Frost was an American 19th century landscape painter who accompanied the construction of the San Francisco–Moscow telegraph line. Probably he liked his stay in Russia/Siberia and was sad when he had to go back to the US.

https://www.sphinxfineart.com/media/LeSphinxMedia/Object/Documents/Frost - Six Drawings.pdf

George Frost Kennan was an American diplomat who was ambassador in Moscow for a short period due 1952. Further, see the comment of @Rat_in_a_hat@lemmy.ca