Leonard, according to sources, has grown frustrated with how the organization handled his quad injury and feels the franchise turned on him once he sought a second opinion.
Leonard has Los Angeles -- preferably the Lakers -- at the center of his preferences for a trade destination, league sources told ESPN's Adrian Wojnarowski.
A source with the Spurs told ESPN that Leonard hasn't asked them for a trade.
If Leonard does become available in trade talks, the Boston Celtics will be interested in probing the Spurs about a deal, league sources told Wojnarowski. Boston inquired about a trade before the February deadline, sources said.
Leonard is eligible to receive a five-year, $219 million contract extension from the Spurs this summer. He can opt out of his current deal after next season and become a free agent in July 2019.
There's a feeling of betrayal that, at this juncture, appears irreparable; Leonard isn't concerned about missing out on the supermax, sources said.
Leonard has communicated with Spurs coach Gregg Popovich in recent days, sources say, but the two have yet to speak in person.
Popovich has been out of town all week attending to family business, sources told ESPN's Michael C. Wright. But Popovich and Leonard have reached out to each other on numerous occasions in recent weeks.
Leonard has been training in San Diego the past month, with a source telling ESPN's Ramona Shelburne that he's making "great progress" in his return from the quad injury that forced him to miss all but nine games last season.
After Friday's news broke, the Lakers were down to 6-1 odds at Westgate Las Vegas SuperBook to win next year's NBA title. They opened 20-1 and were 10-1 Friday before the news hit.