Nearly 200 nations faced a Monday deadline to file what the United Nations' climate chief calls "among the most important policy documents governments will produce this century."

Nearly all nations missed a UN deadline Monday to submit new targets for slashing carbon emissions, including major economies under pressure to show leadership following the US retreat on climate change.

The countries signed up to the Paris Agreement faced a Monday deadline to submit new national climate plans to the UN, setting out how they plan to cut emissions by 2035