RIGA—Ukraine urged NATO on Wednesday to prepare economic sanctions on Russia to deter a possible invasion by tens of thousands of Russian troops concentrated within reach of its border. Ukrainian Foreign Minister Dmytro Kuleba said he would make the request to NATO foreign ministers meeting for the second day in Latvia to discuss how to respond to the Russian build-up and avert potentially the most dangerous crisis in relations with Moscow since the Cold War. “We will call on the allies to join Ukraine in putting together a deterrence package,” Kuleba told reporters as he arrived for the talks in Riga. This should include preparing economic sanctions against Russia, in case it “decides to choose the worst-case scenario”, Kuleba said, adding that NATO should also boost military and defense cooperation with Ukraine. Ukraine is not a member of NATO but the U.S.-led alliance has said it is committed to preserving …