KYIV, Ukraine: Ukraine's president replaced his top general Thursday in a shake-up aimed at reigniting momentum in the deadlocked war with Russia, which is grinding into its third year as the country grapples with shortages of ammunition and personnel and struggles to maintain support from the West.

After days of speculation that change was coming, Ukrainian President Volodymyr Zelenskyy said on social media that he was thankful for the service of the outgoing Gen. Valerii Zaluzhnyi — a military leader popular with troops and the general public. "The time for... a renewal is now," Zelenskyy said on X.

Zelenskyy appointed the commander of Ukraine's ground forces, Col. Gen. Oleksandr Syrskyi, to lead the army, which needs a morale boost at a time when the conflict with Russia has been at a near stalemate for months. Syrskyi has been instrumental in Ukraine's biggest successes during the war, including overseeing the defense of the capital in the early days of the invasion.

His ascension marks the most significant overhaul of Ukraine's military leadership since Russia's full-scale invasion on Feb. 24 2022. Zaluzhnyi said in a Telegram message that he agreed there is a "need to change approaches and strategy."

An adviser to Zelenskyy, Mykhailo Podolyak, said on X that Ukraine needs to "prevent stagnation on the front line, which negatively affects public sentiment, to find new functional and high-tech solutions that will allow (Ukraine) to retain and develop the initiative."

Syrskyi, 58, was bestowed with the country's highest honor for his role in repelling Moscow's advance on the capital. He has also been credited with orchestrating the successful counteroffensive in the Kharkiv region.

Ukraine's struggles with ammunition and personnel come on the heels of a failed counteroffensive last summer and as European allies try to bump up their military production. At the same time, a political standoff in the United States is holding up further aid from Ukraine's main supplier.

The Kremlin has lately been focused on taking the eastern Ukraine city of Avdiivka, throwing more troops into the four-month battle and bombarding Ukrainian defenses there.

Before Thursday's announcement, local media had speculated for days that Zelenskyy would sack Zaluzhnyi.

Zaluzhnyi was highly regarded by his troops and by foreign military officials. Some analysts warned that his exit could bring unwelcome disruption, potentially driving a wedge between the Ukrainian army and its politicians, and fueling uncertainty among the country's Western allies.