President Donald Trump made an announcement Monday aligning him more firmly with Ukraine’s defense against Russia’s invasion than ever before.

Ukraine’s Security Service said Sunday they had killed Russian special service agents suspected of gunning down a fellow officer in Kyiv earlier this week, saying it believed Russia’s Federal Security Service was responsible.

The legislation, which would allow the president to levy a 500% tariff on imports from countries that purchase Russian uranium, gas and oil, has gained momentum in the Senate as Trump has signaled he will escalate US action against Russia.