I'm so sorry this happened to you. Unfortunately such robberies happen everywhere nowadays- certainly in London. We need eyes in the backs of our heads. I hope you weren't injured, but I know these things are very upsetting.

Oh sorry for this misfortune! And thank you for your advice we will be careful

Unfortunately, this type of thing is happening everywhere and we all have to be careful and aware of our surroundings.  It seems it is the "way of the world."  I'm very sorry to hear that this happened to you and I thank you for taking the time to alert others that may be travelling to your part of the world.  Take care.

Sorry for your bad experience in Vietnam. actually, I'm Vietnamese. I don'w know exactly where did you come, but I wanna say apologize for what guy did to you. What you remind to everyone that who wanna travel to VN could not be careless even just a moment" is not wrong. But I have to confirm that that things you met yesterday can come to anyone in any country, not only Vietnam. So when emphasizing "Vietnam" word, you need to say clearly and cleverly. I actually don't want everyone who read this discussion to have a bad impression to my country anymore 'cause beside bad guys, we have many beautiful things out there. I do know how angry and sad you are, but there has many bad guys out there not only Vietnam.  Sometimes, you need to ask yourself for keeping your belongings carefully before going out, especially another country. Last, I wanna know where you went and if it's my city now, we may have a coffee. Have best day! 

Thank for advice, I plannig trip to Vietnam early :-D