Writer Robert Clark has warned that Ukraine's failure to launch a strong counterattack would be in Putin's favor and pave the way for him to win his war.
Writing in Britain's Telegraph newspaper, he said Kiev was now preparing for one of the most significant counterattacks since The Battle of Bulge at the end of World War II.
If Ukrainian forces can make significant progress, the momentum of this would eventually lead to the liberation of all their territory.
But if it fails, U.S. political and military support may begin to weaken, and with it Ukraine's future as a sovereign state. This was seen as a real turning point for the war, given tight timelines and the long-awaited delay of the "spring offensive."
He noted that the poorly executed Russian offensive gave Ukraine an opportunity to exploit the weaknesses of its opponent, and bad weather conditions also played a role, which was disruptive to Russian maneuvers. Finally, there is the much-needed anticipation of the promised Western military hardware.
Ukraine needs at least a partial victory this year to regain territory in the annexed regions of Donetsk, Kherson, Lugansk and Zaparozhya.
If these areas remain occupied before Moscow by next year, the Kremlin is likely to be able to stagnate the conflict and keep its forces in Ukraine at a time when U.S. political and financial support is expected to decline.
Leading candidates Donald Trump and Ron DeSantis have indicated that U.S. support for Ukraine is limited, and many in the party seem to believe that Ukraine is Europe's problem and that it should solve it itself.
If Putin manages to annex eastern Ukraine once and for all, he will be able to declare victory, and Moscow will have taken control of the territory between Russia and the Black Sea, so this attack is Kiev's last chance to reassert its legitimate sovereignty.