Houston Rockets coach Stephen Silas referred to disgruntled superstar James Harden's absence from training camp as a holdout on Monday and said there is "no timetable" he is aware of for the perennial All-Star guard to report.

After Harden missed Houston's first team workout Sunday, Silas cited the NBA's COVID-19 protocols as the reason the Rockets' face of the franchise could not practice with the team. However, Harden did not show up for an anticipated individual workout Sunday evening.

Harden, who sources say has requested to be traded to the Brooklyn Nets, has not communicated recently with Silas. A source told ESPN on Sunday night that Harden informed Rockets management that he would report soon, but Silas expressed uncertainty about when the 2017-18 MVP would rejoin the team.

"There is no timetable, as far as I know," Silas said after Monday's practice. "It is a setback. You want your best player to be here."

Silas said he did not know whether Harden had returned to Houston. Harden posted pictures on Instagram over the weekend of him attending rapper Lil Baby's birthday party in Atlanta, and videos and pictures of Harden hanging out in Las Vegas nightclubs have circulated on social media in the last couple of days.

The NBA has not announced any disciplinary action due to Harden's violations of the league's COVID-19 protocols, which require players to quarantine except for essential activities and team-sanctioned workouts and forbid players from attending parties and clubs.

Harden is also subject to be fined for failing to report to training camp, but Silas said that has not been a subject of discussion at this point.

"I've been in situations before where it was a holdout, and we just kind of handled each individual situation on its own merit and individually," Silas said. "As far as any sort of punishment, we haven't even crossed that bridge yet. We're just trying to work piece by piece."

The Rockets have been adamant that they will not be rushed into trading Harden, who has two seasons plus a player option for a third year remaining on his contract.

Silas, who was hired this offseason to replace Mike D'Antoni, declined to speculate on the point that Harden is attempting to make by failing to report for training camp.

"I have no clarity about the message, honestly," Silas said. "I take it basically at face value that he's not here. What the reasoning is, is on him. He's the one who can explain why or why not he's not here. For me to make inferences and think about the possibilities isn't real to me. What's real is he's not here, and he has a reason, but that's on him to tell whoever what his reason is."