The United States and NATO are shipping weapons into Ukraine at break-neck speed, including highly sensitive items such as shoulder-fired missiles called Man-Portable Air-Defense Systems (MANPADS) that can take down aircraft.
The Western arms deliveries, another one of which is expected to arrive in the coming hours, have been vital to enabling Ukrainians to fight the invading Russians forces far more effectively and fiercely than US intelligence expected.
But moving those amounts of weaponry into the largest conflict in Europe since World War Two carries with it risks that some could fall into the wrong hands -- a possibility the West has considered.
"Frankly, we believe that risk is worth taking right now because the Ukrainians are fighting so skillfully with the tools at their disposal and they're using them so creatively," a senior US defense official said on Friday when asked about that danger.
Highly portable missiles such as Stinger surface-to-air missiles -- which are a type of MANPAD -- can help win wars, but in the past they have also been lost, sold, or wound up in the arsenals of extremist groups.
For example, hundreds of Stingers supplied by the United States were seen as key to helping mujahideen rebels drive Soviet forces out of Afghanistan in a conflict that spanned the 1980s and 1990s.
But the United States subsequently spent years trying to recover unused MANPADS from that country and from other conflict zones around the world.
In a Pentagon-financed study in 2019, the RAND Corp. think-tank estimated that upwards of 60 civilian aircraft have been hit by MANPADS since the 1970s, killing more than 1,000 civilians. As of 2019, 57 non-state armed groups were confirmed to possess or suspected to possess MANPADS.
Russia was "far and away the single largest exporter of MANPADS", RAND Corp. said, with more than 10,000 systems sold between 2010 and 2018 to countries including Iraq, Venezuela, Kazakhstan, Qatar, and Libya.
The United States and NATO have not disclosed how many MANPADS have been transferred to Ukraine since the start of the invasion, which is now in its third week.
So far, Russia has not targeted Western weapons convoys headed into Ukraine and the senior US defense official said the United States had not seen any Western-supplied inventory falling into Russian hands.
But that could change.
At a Friday meeting of Russia's Security Council, Defense Minister Sergei Shoigu talked about potential future seizures of Western-made Javelin anti-tank weapons and Stingers. They should be handed to Russian-backed forces in the breakaway Donbass region of eastern Ukraine, he said.
Russian President Vladimir Putin publicly backed the idea.
"As to the delivery of arms, especially Western-made ones which have fallen into the hands of the Russian army - of course I support the possibility of giving these to the military units of the Lugansk and Donetsk people's republics," Putin said.
"Please do this," Putin told Shoigu.
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