What lies beyond Marismik la? Is it true that there is "Hot Springs" called "Tso-Galu" about 15 km from there?

I read in a Car Magazine(Overdrive) that they wanted to go beyond Marismik La but couldn't. They also had ITBP jawan accompanying them.Usually Jawans don't accompany tourists. So what is beyond that place. I know for a fact that its very close to China border, but so is Nathu-La. But there we can drive right upto the border. So why not here ??