he was already a 2nd lieutenant in a unit. he sabo'ed a lieutenant x, which was one rank above him.
https://www.asiaone.com/News/The+Straits+Times/Story/PM+Lee%27s+son+in+NS+reprimanded+by+SAF.html
here's his letter to top dogs in mindeaf, and it was leaked somehow and circulated on the internet.
"On Wednesday after I had completed my personal investigation and confirmed that these events had indeed transpired, I informed our OC of these offences. Our OC spoke to LTA X regarding these issues, and let him off with a warning.
I would like the story to end here, however LTA RX was again on duty at ____ Camp for _________ on the following Saturday the 28th of April. At 0030 hours on Sunday the 29th of April I received a message from the duty personnel. The duty personnel of the platoon had just spotted LTA X’s car, a white Mitsubishi lancer driving out of camp. . . . They also informed me that LTA X was no where to be found, not in any of the bunks nor any of the offices.
. . .
When confronted by our OC, LTA X told him that indeed it was his car driving out of camp, he claimed however, that it was not him driving the car but that he had lent it to friend to drive out of camp. After checking with the person in question this was established to be untrue. Finally, LTA X admitted that he had lied, and that is was he who had left camp.
I have been informed that LTA X was to be given 10 extra duties, though this may be considered an extremely light punishment there is a further problem. To date, which is to say, 2 months from the incidents, none of the duties have been published in the battalion RO, in addition, LTA X has not served any of the extra duties he was supposedly awarded."