Bangladesh, Sept. 20 -- US President Donald Trump's decision to sign sweeping new legislation expanding sanctions against Russia marks another major escalation in Washington's economic campaign against Moscow. The legislation gives the White House authority to impose tariffs of up to 100 percent on goods from countries that are among the largest buyers of Russian oil and gas.

On paper, the objective is straightforward: increase the economic cost of Russia's war effort and strengthen Washington's leverage over Moscow. In practice, however, the new sanctions could create a far more complicated chain of consequences-one that reaches from the Kremlin to Asian energy markets and ultimately to American fuel pumps.

The legislation, known as t...