Ukrainian law enforcement officials believe they have evidence of wrongdoing by American Democrats and their allies in Kiev, ranging from 2016 election interference to obstructing criminal probes. But, they say, they’ve been thwarted in trying to get the Trump Justice Department to act.

Kostiantyn Kulyk, deputy head of the Prosecutor General’s International Legal Cooperation Department, told me he and other senior law enforcement officials tried unsuccessfully since last year to get visas from the U.S. Embassy in Kiev to deliver their evidence to Washington.