According to the prosecutor’s office, it's because they're accused of having links to the network of US-based cleric Fethullah Gulen.
Ankara says it was him who orchestrated a 2016 attempted coup.
Those who are facing jailtime include three colonels, eight majors and 10 lieutenants.

Israel warns Lebanon of 'heavy price' as week's death toll nears 300
Israeli settler fatally shoots Palestinian in West Bank
Israel carries out rare airborne raid in Lebanon; 16 killed in strikes
US skips congressional review to approve arms sale to Israel
Flash floods in Nairobi kill 23, disrupt flights at major airport
Russia hits Ukraine with drones, missiles, kills at least 10 in Kharkiv
Partial resumption of air navigation in Qatar
Kuwait and Qatar thwart fresh wave of Iranian attacks
