In the run up to Republic Day on Jan 26, the Delhi airport and Hindon air base in nearby Ghaziabad were put on heightened alert Saturday.
"It is a routine alert done ahead of Republic Day," a senior Indian Air Force (IAF) official said, requesting anonymity.
All the air defence components have been put in a state of utmost readiness.
"The Delhi Integrated Air Defence has been put on high alert. The air defence at the airbases in and around the capital will be in a state of readiness to counter any incoming threat from the sky," the official added.