<a href="mailto: dvsavini@cbs.com; mhlebeau@cbs.com; mayoungerman@cbs.com" target="_blank">Send Your Tips To Dave Savini</a>By Dave Savini

CHICAGO (CBS) — A major security breach by two teenagers on a European class trip. They packed military grade munitions in their bags, then were busted by federal agents at O’Hare International Airport.

The shells date back to World War I, but these types of artillery can still pack a deadly punch. In this case, the artillery shells ended up being harmless, but the fact that they got through London’s Heathrow Airport raises serious questions about security there.

CBS 2’s Dave Savini looked into how these artillery shells ended up on United Airlines flight 1749 from London to Chicago on Monday.

Ross Rice, CBS 2’s security consultant, says flights heading to the United States have to follow U.S. security and screening rules which would include prohibiting military relics, that have not been inspected, from getting on a passenger plane.

“You just can’t bring it on a commercial airlines flight,” said Rice. “It would not have met the standard.”

These French, 75 mm shells were found by the U.S. Transportation Security Administration (TSA) in Chicago, when the teens checked their bags for the next leg of their trip to Seattle. Rice says the screening process failed overseas.

Rice also says there is a big market for war relics, which can seem unarmed and harmless, but time can make them more dangerous.

“In fact, it is more explosive now than when it was first manufactured, because the internal components of the shell or grenade have degraded over the years,” said Rice.

Finding military weapons on planes is less common, unlike other weapons. Last year, 1800 guns were caught at airport checkpoints across the U.S. Weapons of all sorts that could endanger the flying public.

The teens in this case, turned over the shells to the TSA and are not being charged. They apparently got the relics from an old artillery range next to a museum.

United Airlines says they are not responsible for the luggage screening. We reached out to officials at London’s Heathrow airport and have not yet received a response.

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