Russia has managed to overcome sanctions and export controls imposed by the West to expand its missile production beyond prewar levels, according to U.S., European and Ukrainian officials, leaving Ukraine especially vulnerable to intensified attacks in the coming months.

In addition to spending more than $40 billion providing weapons for Ukraine, the United States has made curbing Russia’s military supply a key part of its strategy to support Kyiv.

But by the end of 2022, Moscow’s military industrial manufacturing began to pick up speed again, American officials who spoke on condition of anonymity to disclose the sensitive assessment now concede.

Russia’s re-energized military production is especially worrisome because Moscow has used artillery to pound Ukrainian soldiers on the front lines, and its missiles to attack the electric grid and other critical infrastructure, and to terrorize civilians in cities.

With revenue from high energy prices, Russia’s security services and ministry of defense have been able to smuggle in the microelectronics and other Western materials required for cruise missiles and other precision guided weaponry.

“Because the controls were having a real impact, the Russian government didn’t just throw up their hands and say, ‘You got us, we give up,’ ” said Matthew S. Axelrod, the Commerce Department’s assistance secretary for export enforcement.

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