What if I'm not an US citizen and a company from US (threaten to) sues me over a .com domain registered through an non-US registrar? Should I hire an US lawyer?

What if I'm not an US citizen and a company from US (threaten to) sues me over a .com domain registered through an non-US registrar? Should I hire an US lawyer? Where does the trial take place: in US or in my country? Let's say I get an email like the one OP got but I don't understand english and I take no action... Will the non-US registrar give them my domain by default?