The defense industry is certainly vulnerable to corruption. Yet, the recent case in which seven people, including retired and serving military officers, were indicted for trading military secrets is truly upsetting.

State and military prosecutors said earlier this week that after a joint investigation, they indicted three active military officers and four others on charges of violating the Military Secrets Protection Act.

They said two executives of a defense contractor, one of them a retired Navy captain, and two “consultants,” both retired military officers, were indicted for obtaining military secrets on 31 occasions and handing them over to 25 local and foreign defense suppliers between 2008 and June 2014.

Three military officers ― an Air Force lieutenant, an Army major and a colonel at the Defense Acquisition Program Administration ― were charged with handing over the classified information in return for money and free entertainment. The Class-II and Class-III secrets included information on small gunships, new coastal defense frigates currently under development, maritime surveillance systems and an anti-GPS jamming system.

What distinguishes this case from other previous corruption cases is that the uniformed officers leaked the confidential information in the most daring manner yet.

Prosecutors said that in most past cases, officers took out classified information “a bit at a time,” by, for instance, writing down memos from secret papers. This time, the officers leaked copies of whole pages and even took pictures of classified papers and transmitted them by mobile messenger programs.

This shows that our military is armed with a far less effective system to protect secrets than some high-tech businesses, like Samsung Electronics. They should think about asking for help from Samsung’s security office.

What should be done urgently is to make it harder for retired military officers to get jobs in the defense industry. As shown in the latest case, military officers and their retired former colleagues are easily drawn into collusion.

Corrupt ties like these were one of the causes of the sinking of the Sewol ferry, which is forcing the government to curb revolving-door appointments and impose further limits on retired civil servants getting jobs in the private sector. Priority in this endeavor should be put on the defense industry.