Flush with success in supporting his ally in Syria, Vladimir Putin has a new ambition: supporting another one, this time in Libya. The effort is beginning to undermine the U.N.-backed government there.

Russian President Putin’s government is befriending a powerful military leader, Khalifa Haftar, who now controls more territory than any other faction in the tumultuous, oil-rich North African state. In two visits to Moscow in the past half-year, Haftar met the defense and foreign ministers, plus the national-security chief, to seek support. A top ally also visited last week and Russia is supplying funds and military expertise to Haftar’s base in the east.

“The longer we wait, the more likely it becomes that Haftar wins,” said Riccardo Fabiani, a senior Middle East and North Africa analyst at Eurasia Group in London. “It’s clear he’s getting military, financial and diplomatic support.” […]