The sanctions could break a diplomatic deadlock by making it more difficult for India to continue buying from Russia, a point of contention between President Trump and Narendra Modi.
While oil markets reacted strongly to the sanctions, analysts said the measures were unlikely to significantly change President Vladimir V. Putin's war calculations.
The sanctions against oil giants Rosneft and Lukoil followed months of calls from Ukrainian President Volodymyr Zelenskyy to hit Russia with harder sanctions on its oil industry.
