MOSCOW  With an ambitious new pipeline planned to run along the bed of the Baltic Sea, the Russian natural gas giant Gazprom is driving a political wedge between Eastern and Western Europe.

While the Russian-German pipeline offers clear energy benefits to Western Europe, Central and Eastern European leaders fear it could lead to a new era of gas-leveraged Russian domination of the former Soviet bloc. With its gas wealth and eyebrow-raising network of personal ties, Russia has divided members of the European Union that have vowed to act collectively to protect their security.

Currently, Russian gas has to be piped through Eastern Europe to reach Western Europe. If Russia shuts off the gas to pressure a neighbor in the east, it is felt in the more powerful, wealthier countries to the west, where it touches off loud protests.

The new Nord Stream pipeline will change that equation. By traveling more than 750 miles underwater, from Vyborg, Russia, to Greifswald, Germany, bypassing the former Soviet and satellite states, it will give Russia a separate supply line to the west.