In May 2022, the Ukrainian outlet Ukrainska Pravda reported, citing sources close to Zelensky, that Johnson made a surprise visit to Kyiv on April 9, 2022, shortly after Ukrainian and Russian negotiators had made progress toward a draft agreement in Istanbul. According to these sources, Johnson delivered two messages: first, that Putin was a war criminal who should be pressured rather than negotiated with, and second, that even if Ukraine was willing to sign a deal with Russia, the West—particularly the UK and US—was not prepared to support it. Three days later, Putin declared the talks had reached a "dead end," and negotiations stalled.

David Arakhamia, a key member of Zelensky’s negotiating team in Istanbul, added fuel to this narrative in a November 2023 interview. He stated that after returning from Istanbul, where a tentative framework had been discussed (including Ukrainian neutrality in exchange for security guarantees), "Boris Johnson came to Kyiv and said that we would not sign anything with them at all, and let’s just fight."