When Donald Trump promised to raise U.S. natural gas exports in Europe in a speech in Poland, he was cheered to the rooftops.

Such a reaction will have troubled executives at Gazprom, Russia’s state-owned energy group, as it marks an escalation in the battle over gas supplies in the prized European market.

That fight has been years in the making, with the growth of U.S. LNG exports set to challenge the established supplies of the company.