Putin wants to crack down on immigration after the Moscow attack. That would make the nation's labor shortage even worse.

• Russia is looking to crack down on migrants after the terrorist attack at a Moscow concert hall.
• But those measures could end up harming its economy, because there's already a shortage of available workers.
• Russia has up to 5 million migrant workers currently in the country, Bloomberg Economics estimated.

Russia's immigration crackdown could end up delivering another serious blow to its economy, with the nation already suffering from a severe shortage of workers.