The timing for any move to break the deadlock has emerged as a pivotal strategic decision for Ukraine’s government. Both sides are preparing for a protracted war, but Ukraine has greater incentive to try to avoid it by undertaking risky maneuvers as early as this fall — before the rainy season closes the window on possible offensives over open fields.

From the Ukrainian perspective, the mostly static trench fighting cannot go on indefinitely. Leaving Russia in control of much of the southern coastline would cripple Ukraine’s economy, already cratering from the war and propped up by Western aid.

The initial target of any counterattack is widely assumed to be Russian positions on the western bank of the Dnipro River. Move too soon, though, and the Ukrainian army may prove unready and insufficiently armed to ensure victory, military analysts say. Wait too long, and political backing in Europe may waver as energy prices soar.

Political pressure is mounting for President Volodymyr Zelensky of Ukraine to make a move even as it remains unclear whether his military has amassed the necessary weaponry and manpower.