Afghanistan’s President Hamid Karzai has refused to sign a security deal with the United States, the White House said, opening up the prospect of a complete withdrawal of U.S. troops from the strife-torn nation next year.

“The purpose of Geneva-2 is not to have an armchair discussion about Syria, it’s to have mutual agreement between regime representatives — without Assad — and the moderate opposition in order to form a transitional government,” Laurent Fabius told French radio.

France said Tuesday it would send hundreds of extra troops to the strife-torn Central African Republic after the UN warned the country was descending into “complete chaos”.