Western air defence systems remain "crucial" for Ukraine, the Institute for the Study of War (ISW) has said.
The US-based thinktank said both Russian and Ukrainian forces were engaged in a "tactical and technological offensive-defence race", with both sides experimenting and adapting their long-range strikes and air defences.
"The continued and increased Western provision of air defence systems and missiles to Ukraine is crucial as Russian forces continue to experiment with new ways to penetrate Ukrainian air defences," it said in its report.
The thinktank assessed that the inclusion of Western-provided systems into Ukraine's air defence umbrella was "essential" to Ukraine's ability to defend itself.