Russia gains advantage in eastern Ukraine as forces learn from past mistakes, U.S. officials say

The United States does not expect new weapon systems recently delivered to Ukrainian forces, including the HIMARS multi-missile launch system, to instantly change the battlefield situation, in part because these systems have so far been deployed with both a limited range and a limited number of missiles to ensure they are not fired into Russian territory . In addition, Russian forces have been able to destroy some of the new Western-supplied weapons, including M777 howitzers, in targeted attacks.

The American assessments, which increasingly imagine a long and punitive struggle in eastern Ukraine, come as the months-long war that has reached a crucial moment in recent days. Ukraine’s military has burned through Soviet – era ammunition to fit older systems, and Western governments are facing a difficult decision on whether to continue to increase their aid to the country.

The American assessments paint a gloomy picture of the future of the war with large losses of personnel and equipment on both sides. US officials believe Russian forces plan to sustain intense attacks in the east, marked by heavy artillery and missile attacks, with the intention of eroding Ukrainian forces and NATO’s determination over time.

Russia’s progress has been highlighted in recent days following Ukraine’s defense of Lysychansk – the last city in the Luhansk region it still has – became much more flimsy. In the last few days, Russians have moved into several villages south of Lysychansk, though not without suffering losses from Ukrainian artillery fire.

In the coming weeks, Ukrainian President Volodymyr Zelensky will almost address the forthcoming G7 and NATO summits, senior US administration officials have said, with the leader seeking to support Western support for his country. During the G7, President Joe Biden will unveil steps with other leaders to increase pressure on Russia for its invasion. And in NATO, the United States will announce measures to “strengthen European security along with expected major new contributions from allies,” an official said.

Members of the Ukrainian parliament have told US lawmakers that the Russian military has calculated how much ammunition Western allies have in stock for the Ukrainian military’s mainly Russian-made artillery – and plans to wait for Ukrainian forces to run out over time.

“Putin is not deterred and I do not think he will ever be deterred,” the rep said. Mike Quigley, an Illinois Democrat who sits on the House Intelligence Committee, told CNN.

“This war can last for years,” he added.

At home, the United States and NATO partners are beginning to see the limits of their own supplies of certain advanced weapons, including shoulder-fired anti-aircraft missiles and Javelin anti-tank missiles. These weapons systems have their own complicated supply lines, which means that it can take years to replace the thousands of such missiles already delivered to Ukrainian forces.

Meanwhile, the US Department of Defense’s watchdog has opened an evaluation of the department’s plans to rebuild its own ammunition and equipment stocks, while continuing to supply significant quantities to Ukraine, the agency announced on Wednesday.

“The purpose of this evaluation is to determine the extent to which the DOD has planned to rebuild its equipment and ammunition delivered to Ukraine,” the department’s inspector general said in a statement.

CNN’s Devan Cole, Katie Bo Lillis, Barbara Starr, Natasha Bertrand, Oren Liebermann, Tim Lister, Donald Judd and Kevin Liptak contributed to this report.