`The security measures were tightened at the Bulgarian borders, airports and ports, `Valeri Grigorov, Director of the National Police Border Services said. The measures were enhanced after the start of the military operation in the United States. The security measures at the Sofia airport were not changed. Three methods are used to check the security at the airport: primary, secondary and check of the aircraft. On October 8, a day after the military action in Afghanistan, the situation in the airport remained stable and normal. There were no queues in front of the departing or arriving gates, Info Radio reported.