They are the terrorists' trump card -- and our Achilles' heel.

It may be that the Sinai Peninsula is [Egypt's] Achilles' heel. [Terrorist groups have] gone up and down the coast and hit the main tourist resorts.

All interesting heroes have an Achilles' heel.

Anybody who has political ambition has an Achilles heel.

The Achilles Heel of the Americas was the lack of cultural confidence typical of new settlers.

That's been the Achilles heel of our team the whole year.