Less than a week after the New York Yankees shut down starter Luis Severino due to forearm discomfort, the team announced Tuesday that the right-hander now needs Tommy John surgery.

"His plan is to have it done as soon as possible,'' Yankees general manager Brian Cashman said Tuesday.

Severino was scratched from throwing his second bullpen session in camp last week and didn't take part in pitchers' fielding drills. After the workout, manager Aaron Boone said Severino had been dealing with forearm discomfort that started after Game 3 of the American League Championship Series against the Houston Astros.

The Yankees will already be without pitcher James Paxton through at least April after the left-hander underwent a procedure to remove a cyst as well as a microscopic lumbar surgery.

Cashman said last week that Severino had two MRIs -- one in December and another in January -- and a CT scan after complaining of discomfort, and all tests had been negative. But the Yankees sent him for further testing. Cashman said Tuesday that a dye contrast MRI revealed the partial tear of the UCL.

In January, Severino was treated with anti-inflammatories and said he felt fine, Boone said. Testing revealed a "loose body" near his elbow, which the team believes is an incidental unrelated finding. Once Severino ramped up his throwing program this spring, he stayed away from his changeup.

Severino, who turned 26 on Thursday, didn't pitch in the majors last season until September after spending most of the season on the IL because of injuries to his right rotator cuff and lat muscle. He made three starts.

The two-time All-Star was coming off his best season in 2018 when he went 19-8 with a 3.39 ERA and 220 strikeouts in 191⅓ innings.

Severino signed a four-year, $40 million extension almost exactly a year ago, but he has thrown just 20⅓ innings since then.

ESPN's Marly Rivera and The Associated Press contributed to this report.