Tensions between the U.S. and Russia increased again today after the U.S. announced new sanctions, a Russian plane shot down a Ukrainian fighter jet, a Malaysia Airlines plane crashed in Ukraine, and Vladimir Putin hinted at retaliatory sanctions against the U.S. and Europe. When tensions between major economic powers rise like this, stocks generally fall.

The Dow Jones Industrial Average (DJINDICES:^DJI) has fallen 130 points near the end of trading, but the bigger sell-off is going on in Russia: The Market Vectors Russia ETF is down 7% today.

Two U.S. stocks worried about Russia
Most companies on the Dow Jones Industrial Average have some dealings in Russia, but two notable ones are Visa (NYSE:V) and ExxonMobil (NYSE:XOM), which are down 1.8% and 1%, respectively.

As a global company, Visa can be caught in political conflicts.

Visa generates 4% of its revenue in Russia, and its partner Gazprombank is one of the targets of U.S. sanctions. Gazprombank and others won't be allowed to access capital in U.S. markets as part of an effort to put pressure on Russia to leave Ukraine's Crimea region. Right now Visa's business will go on as usual, but this recalls Russia's earlier pressure for Visa and other payment processors to pay billions of dollars for access to the Russian market. So far those threats haven't led to any payment or exit from the country, but today's actions are a step in the wrong direction.  

A bigger impact could be felt by ExxonMobil, which has a massive joint venture with Russian firm Rosneft to explore the Arctic, conduct Siberian fracking and Black Sea drilling, and construct natural-gas export terminals. The two companies are tied at the hip, and at the very least the tension between Washington and Moscow makes these massive partnerships uncomfortable. Right now, investors shouldn't panic, but Putin's reaction to recent events and his potential retaliation against U.S. companies could hit ExxonMobil where it hurts -- in the pocketbook.  

These kinds of tensions can hit stocks in the short term, but in the long term, the odds of a major U.S.-Russia conflict are low. Look at major dips as a buying opportunity, because there shouldn't be a big impact on earnings for Visa or ExxonMobil unless they're completely kicked out of Russia, which is unlikely.