"“The territorial integrity of Ukraine has never been, and will never be, a subject for discussion or compromise. "
But that's not what history shows: Crimea was precisely the subject for not only discussion and compromise when the territory, which had been recognised as part of the RSFSR (Russia) within the Soviet Union, was transferred as a gift to the Ukrainian SSR, due to 'close ties' to commemorate the Union of Russia and Ukraine Tercentenary in 1954. Those interested, I would suggest, might be best to read, 'Why Did Russia Give Away Crimea Sixty Years Ago?' by Mark Kramer, Director of Cold War Studies at Harvard University for the Wilson Centre (https://www.wilsoncenter.org). See here: https://www.wilsoncenter.org/publication/why-did-russia-give-away-crimea-sixty-years-ago.
"“The territorial integrity of Ukraine has never been, and will never be, a subject for discussion or compromise. "
But that's not what history shows: Crimea was precisely the subject for not only discussion and compromise when the territory, which had been recognised as part of the RSFSR (Russia) within the Soviet Union, was transferred as a gift to the Ukrainian SSR, due to 'close ties' to commemorate the Union of Russia and Ukraine Tercentenary in 1954. Those interested, I would suggest, might be best to read, 'Why Did Russia Give Away Crimea Sixty Years Ago?' by Mark Kramer, Director of Cold War Studies at Harvard University for the Wilson Centre (https://www.wilsoncenter.org). See here: https://www.wilsoncenter.org/publication/why-did-russia-give-away-crimea-sixty-years-ago.
Sikorski is alas, almost a decade too late with his suggestion.