IndiGo, India’s biggest airline, grounded at least one aircraft after it received a call warning of a possible bomb a day after terrorist attacks in Brussels killed at least 35 people. The airline, operated by InterGlobe Aviation Ltd., declined to confirm a Press Trust of India report that 9 other aircraft were also grounded following the bomb threat call. IndiGo said it has started additional security measures. Authorities are on the edge around the world, beefing up security around airport terminals following the bombings in the Belgian capital on Tuesday. Jet Airways India Ltd., India’s second-largest carrier, said it grounded and checked five flights from New Delhi on Tuesday after receiving a “security alert.” Incheon airport, which serves Seoul, said it will add about 700 additional staff to monitor security and detect explosives. Asian airports had stepped up checks since the Paris terrorist attacks and the suspected bombing of a Russian aircraft by the Islamic State last year.  Narita Airport, east of Tokyo, has also strengthened patrol of any suspicious objects.