What happened

Shares of aerospace giant Boeing (BA -0.76%) are among the highest-profile victims of today's sell-off on the latest escalation of Russia's moves against Ukraine. As of 2:05 p.m. ET Tuesday, Boeing stock was down 5.2%, roughly three times the loss of the S&P 500 as a whole.

So what

Why would a full-scale Russian invasion of Ukraine be bad news for Boeing?

For one thing, it could interrupt supplies of Russian titanium that Boeing needs to build its airplanes. Judging from past comments by the company, Boeing spends roughly $9 billion every 10 years on Russian titanium.

But the U.S. has already begun imposing new economic sanctions on Russia to punish President Vladimir Putin's latest round of East European aggression. And the farther Russian tanks roll onto Ukrainian territory, the more significant and wide-ranging the economic sanctions are likely to become.

Map of Moscow under a magnifying glass.

Image source: Getty Images.

Now what

Potentially, it could soon become outright illegal to do business with Russian companies, and that's a danger that could bite Boeing two ways.

On the one hand, sanctions against Russian purchases of American products could shut Boeing out of the Russian airline market entirely. On the other hand, they could threaten Boeing's supply of metals needed to build airplanes to sell to anybody else. Not only is Russia the world's No. 2 producer of the metal, but the No. 5 producer is Ukraine. (And suffice it to say that source of supply is looking increasingly tenuous.)

All that being said, Russia and Ukraine aren't the only places Boeing can get the titanium it needs. Japan is the No. 3 producer of the metal globally, and India is No. 6. While today's news is troubling for all sorts of reasons, therefore, I hardly think it's a good reason to sell Boeing stock.