Ukraine will keep targeting Russian oil-refining facilities despite U.S. discontent with its campaign, according to President Volodymyr Zelenskyy, who warned that Kyiv¡¯s forces may be forced to retreat ¡°step by step¡± without more military aid from allies.

The drone attacks are in retaliation against Kremlin strikes on Ukraine¡¯s energy grid and part of an effort to compel Moscow to stop them, The Washington Post¡¯s David Ignatius wrote in a column, citing an interview with Zelenskyy done Thursday in Kyiv.

Ukrainian forces have attacked more than a dozen refineries inside Russia with explosive-laden drones over the past month, slashing fuel production. But the strikes irked Kyiv¡¯s allies in U.S. who are concerned about rising domestic fuel prices in an election year, the Financial Times reported last week, citing people familiar with the issue.