11.  The accidental downing of the Blackhawks was one of the most deadly episodes of mistakenly firing on friendly forces in recent memory.

12.  The recent NATO briefing contends that allied efforts to indentify friendly forces have a solid foundation in technologies already being pursued by the United States and others.

13.  The society is open to any American flier who was shot down behind enemy lines in any war but who made it back to friendly forces.

14.  All allied troops operating in the Kandahar area are supposed to be aware of friendly forces.

15.  All forces operating in the Kandahar area are supposed to be aware of friendly forces.

16.  And the United States also allows Colombia to use its U.S. counternarcotics equipment to help friendly forces under attack and endangered by guerrillas.

17.  In other mistaken raids, U.S. bombs and troops killed civilians or friendly forces.

18.  Rear Adm. Mark Fitzgerald, the Roosevelt battle group commander, said the pilots were avoiding hitting friendly forces or causing collateral damage.

19.  Special operations troops specialize in undercover search-and-destroy missions, quick commando raids, psychological warfare and training of friendly local forces.

20.  The Afghan fighters wore green wool uniforms, and pinned to their black hats were fluorescent pieces of paper to alert U.S. helicopter pilots that they were friendly forces.