Out at sea, far from prying eyes, work on the unfinished Nord Stream 2 pipeline is in full swing, despite criticism from the international community and US sanctions. Russia and Germany want to complete the gas pipeline linking the two countries as soon as possible, but others are doing all they can to stop it happening. Environmental NGOs, Europe, Ukraine and the US are all set on preventing a project which is as much geopolitical as it is economic. Our correspondents in Russia, Germany and Ukraine report.