LONDON, Dec 7 (Reuters) - Russian President Vladimir Putin said on Wednesday that his army could be fighting in Ukraine for a long time, but he saw "no sense" in mobilising additional soldiers at this point."As for the duration of the special military operation, well, of course, this can be a long process," Putin said, using his preferred term to refer to the Russian invasion, now in its 10th month.In a televised meeting of his human rights council that was dominated by the war, Putin said Russians would "defend ourselves with all the means at our disposal", asserting that Russia was seen in the West as "a second-class country that has no right to exist at all".He said the risk of a nuclear war was growing - the latest in a series of such warnings from Moscow - but that Russia would not threaten recklessly to use such weapons.Since then, Russia has been forced into a series of significant retreats, but Putin has said he has no regrets about launching the most devastating war in Europe since World War Two."