The arrival of the latest batch of F-35A stealth fighters from the U.S. was also kept low-key, though the Air Force is holding a closed-door ceremony marking their deployment on Tuesday.

There will be none of the usual brass bands and ceremonial marking the purchase and handover, and the government will not announce the date of the drones' arrival.

Military authorities have decided to keep under wraps the entire process of purchasing Global Hawk unmanned surveillance and reconnaissance aircraft from the U.S.

South Korea had planned to take delivery of the Global Hawks on Tuesday, but poor weather delayed their arrival.

"We decided preemptively not to announce the arrival of the Global Hawk," a military source said Monday. He said the decision was made because of "the nature of the surveillance and reconnaissance assets."

In other words, since they are spy drones they should be deployed clandestinely.

But that rationale failed to quell concerns in the ranks that the government is only worried about agitating North Korea, which typically seizes on such purchases as a pretext for provocations and other antics.

The Global Hawk is capable of identifying objects measuring just 30 cm from an altitude of 20 km and has a maximum range of 3,000 km flying around the clock.

South Korea had been wanting to buy them since the Roh Moo-hyun administration (2003-2008) but was thwarted by U.S. fears of classified technology leaking. A deal was finally reached during the Park Geun-hye administration (2013-2017). South Korea has spent W880 billion to buy four of the drones, which are slated for delivery by early next year (US$1=W1,174).