<h1>US official warns secondary sanctions and reciprocal tariffs on Russian crude could cripple economy, pressure negotiations, seeks European coordination</h1> A senior US Treasury official said additional secondary sanctions and reciprocal tariffs targeting purchasers of Russian crude could critically damage the Russian economy and pressure its government to negotiate, but urged coordinated action with European partners. The administration has already imposed a 50% duty on one major oil-importing country for buying Russian crude, prompting that country to call the measures unjustified and defend its energy purchases as driven by national interest and market dynamics. Officials framed the measures as aimed at disrupting financing for the conflict in Ukraine and emphasized timing relative to battlefield resilience.