By holding nuclear drills and boasting about the successful test of a pioneering nuclear-powered cruise missile, Russian President Vladimir Putin is sending a message to President Donald Trump: Moscow wouldn’t be cowed into concessions on Ukraine. Facing Trump’s call for a quick ceasefire and bruising, new U.S. sanctions on Russia’s oil industry, Putin again is reminding the U.S. and other Western allies about Moscow’s nuclear arsenals to back his longstanding and maximalist demands. He has said Ukraine must pull back its forces from the four regions that Russia illegally annexed but never fully captured and abandon its bid to join NATO — demands rejected by Kyiv and its Western allies.