Grenade, ferret, gas can found in airports

For all of the alerts and warnings about the possibility of terrorist activity in recent days, there are signs that basic airport security still has huge holes. Some examples:

A man flies from Venezuela to London where a terminal at Gatwick Airport is shut down after the man is found carrying a live grenade. A man is arrested during a layover in St. Louis after he kills a ferret he had with him on the first leg of his flight. He told officials he carried the animal aboard in an ice cooler. A Japanese tourist traveling from Jamaica to the Bahamas is arrested in the Miami airport after carrying a barbecue grill and a metal canister of gas through the airport.

Question: Who checked these passengers before they boarded their respective flights?

Answer: Apparently no one.

It is to the credit of alert officials at other airports that they were detained.