________ nations has not ratified the Open Skies Treaty ?

a) US
b) Kyrgyzstan 
c) The Czech Republic
d) Turkey

The Treaty of Open Skies was signed on January 1, 2002. The treaty has 35 signatories including Russia, the US, the UK, Germany, France, Canada, Spain, Portugal, Italy and Greece. Kyrgyzstan is the only nation that has signed the Open Skies Treaty but not ratified it.