Thousands of school bus drivers are being enlisted to serve as an army of eyes and ears against potential future terrorist attacks on US soil.

They may be unlikely foot soldiers in America’s war on terror, but some 30,000 drivers have been trained in how to spot suspicious characters “casing” their route on the daily ride to school and check their vehicles for signs of tampering. The School Bus Watch scheme, funded with a $50m Department of Homeland Security grant, was set up to raise vigilance against terrorist threats across America’s transportation industry, last July.

“We give drivers basic information on how the typical terrorist attack is carried out,” said spokesman John Willard.

“Terrorists don’t wake up on Tuesday morning and decide to blow something up on Tuesday afternoon, they extensively rehearse, so we ask drivers to be aware of strangers who are asking weird questions.”

They’re also taught to go beyond normal safety inspections and check onboard and underneath vehicles for suspicious devices, he said.

Drivers receive an identification number to quote if they need to call a special hotline set up to report suspicious activity, added Mr Willard, who said the scheme had been “inundated” with applications from US education authorities.

America’s 600,000 yellow school buses are icons on the country’s roads, ferrying 24 million pupils to and from school daily.

Kenneth Trump, president of school security consulting firm, National School Safety and Security Services, said the idea they could be targeted by terrorists wasn’t far fetched or unduly alarmist. “It would be naive and foolish to think terrorists would not attack a school bus in the US,” he said.

“It has been done in the Middle East for decades.

“School bus drivers see children day to day and whether you’re talking about the threat of a local molester or of a terrorist, they need to have a much heightened awareness of their surroundings.”