Ukraine crisis: Why a lack of parts has hamstrung Russia's military
Russia's defence firms have been hit not only by Western sanctions but also by a breakdown in business ties with Ukraine.
For decades under Soviet rule, Russia's strategic industries had close links with partners in Ukraine, all centrally controlled from Moscow.
But relations soured last year, with Ukraine's pivot to the West, Russia's annexation of Crimea and the pro-Russian insurgency in eastern Ukraine.
The EU and US banned military exports to Russia, saying Moscow was supplying the insurgents with sophisticated heavy weapons and regular troops. Moscow denied the allegations.
Last month, Russian Deputy Prime Minister Dmitry Rogozin told parliament that Ukrainian components were used in the production of 186 types of Russian military equipment.
That is a serious problem, he admitted, and Moscow could resolve it only by 2018.
Back in June 2014, Ukrainian President Petro Poroshenko ordered a halt to military co-operation with Russia - and that has shut down several projects.
Ukraine hosts the design bureau of Antonov military transport planes. The economic freeze has blocked plans to deliver a new heavy transport plane, the An-70. And this month, Russia stopped producing another transport plane - the An-140.
In February, Russia closed another programme - Rokot space rockets, which had been putting military satellites into orbit.
The Russian navy has suffered too. It was awaiting three Project 22350 frigates (Admiral Gorshkov-class), but they did not arrive because Ukraine did not deliver the turbines for them.
Air transport problems
Communist-era production cycles involved defence plants in several Soviet republics, but they became independent states when the Soviet Union collapsed in 1991.
Since then, Russia has become dependent on Western electronic components - especially computers, vital for all modern armies.
In a high-profile setback for the Russian navy, France cancelled delivery of two Mistral helicopter carriers. France finally agreed on a compensation deal for Russia this week, after long negotiations.
Since 1991, Russia's armed forces have continued to rely on Antonov transport planes - the An-26 (for lighter loads), An-12 (medium loads) and An-124 (very heavy loads). For the heaviest cargoes, Russia also has the Ilyushin-76.
All Antonov planes have Ukrainian components. Experts say suspension of the An-70 programme will not affect the Russian army much, but the lack of components for An-140 production will be a problem.
The Russian air force and navy had already received up to 10 new Antonovs before deliveries stopped.
There is an urgent need to replace ageing An-26 planes - production was discontinued in the mid-1980s.
Russia could revive plans to build a light cargo plane, the Ilyushin-112, but that means finding reliable Russian replacements for Ukrainian components.
"Whatever option it decides to go with, Russia's efforts to revamp its fixed-wing transport capabilities are being affected by the crisis with Ukraine in ways that go beyond the An-140," wrote analyst Gareth Jennings in Jane's Defence Weekly.
Ukraine has also been a key supplier of engine components.
In May, the Ukrainian company Motor-Sich stopped deliveries of helicopter engines for combat helicopters, but continued taking orders for civilian helicopters.
Mr Rogozin said Russia would strive to integrate engine production for the navy and air force, to reduce costs and move away from reliance on Ukrainian and Western equipment.
But a previous Russian attempt to reduce the military's reliance on Ukrainian equipment was only partly successful, Russian military expert Alexander Golts told the BBC.
"We can't take Mr Rogozin's statements at face value. We can believe them only when we see the first Russian gas turbines [for the military]," he said.