New Delhi, Sept. 17 :    New Delhi, Sept. 17:  Airlines in India have begun to take stock of security inside the planes following terrorist attacks in the US. Officials said security inside international aircraft adheres to the regulation of the country the air carrier belongs to, while the airport's security rests with the host country. Several security measures are being considered, including making the cockpit accessible only to the pilot. But a captain of the Indian Airlines said: 'Even if the cockpit is locked and people are barred from entering it, anyone can break in during a terrorist attack.' 'Only if ground airport security personnel keep vigil and scrutinise people like caterers and cleaning people, who have access to the aircraft, can such incidents be stopped. It is very difficult to control hijackers when flying.' According to Veeranna Aivalli, commissioner security of the Bureau of Civil Aviation, security inside the aircraft was stepped up after the hijack of an Indian Airlines flight from Kathmandu in 1999. Sky marshals were appointed to keep vigil inside the aircraft. Two sky marshals with fire arms - that shoot at a lower than normal velocity to prevent a puncture in the cabin - are posted in the aircraft. 'The air marshals are trained in guerrilla warfare,' said Aivalli 'These commandos are mostly present in flights that go to sensitive areas like Jammu and Kashmir and Kathmandu. The identity of the sky marshals on board is disclosed only to the captain,' said a captain of the Indian Airlines.