FARC rebel leader Rodrigo Londono, better known by hs nom de guerre Timochenko(C) and And leadership waves after the opening of ceremony congress at the camp where they prepare for ratifying a peace deal with the government, near El Diamante in Yari Plains, Colombia, September 17, 2016. REUTERS /John Vizcaino

FARC rebel leader Rodrigo Londono, better known by his nom de guerre Timochenko, is seen on a screen during the opening of ceremony congress at the camp where they prepare for ratifying a peace deal with the government, near El Diamante in Yari Plains, Colombia, September 17, 2016. REUTERS /John Vizcaino

FARC rebel leader Rodrigo Londono, better known by hs nom de guerre Timochenko, and leaders sing the anthem during the opening of ceremony congress at the camp where they prepare for ratifying a peace deal with the government, near El Diamante in Yari Plains, Colombia, September 17, 2016. REUTERS /John Vizcaino

Austria's Chancellor Christian Kern arrives for the European Union summit- the first one since Britain voted to quit- in Bratislava, Slovakia, September 16, 2016. REUTERS/Leonhard Foeger

Congo President Joseph Kabila signs the Paris Agreement on climate change at United Nations Headquarters in Manhattan, New York, U.S., in this file photo dated April 22, 2016. REUTERS/Carlo Allegri

A Novartis logo is pictured on its headquarters building in Mumbai April 1, 2013. REUTERS/Vivek Prakash/File Photo

Slovakia's Prime Minister Robert Fico arrives for the European Union summit- the first one since Britain voted to quit- in Bratislava, Slovakia, September 16, 2016. REUTERS/Leonhard Foeger

Formula One - Singapore Grand Prix - Marina Bay, Singapore - 17/9/16 Mercedes' Nico Rosberg of Germany in action during third practice. REUTERS/Edgar Su