SINGAPORE’s threat to match in some form Malaysia’s Road Charge (RC) of RM20 (S$6.60) at the two land entry points in Johor — the Causeway and Second Link — is hardly the type of response we would expect from a neighbour. It is not the kind of attitude that we had hoped for from the island republic. Singapore’s furious reaction to Malaysia’s move appears to have raised the prospect of tit-for-tat retaliation. Singapore had labelled the new levy, which came into effect on Tuesday, as discriminatory and said it would announce details of its retribution in due course. It sounds menacing, indeed. Foreign private-registered vehicles entering Johor will now have to pay the RC, which will be collected each time motorists enter Malaysia via Touch n’ Go cards. After passport clearance, drivers will then proceed to tap their cards twice, at two different terminals — one for the RC and the other for the checkpoint toll. Motorcyclists do not have to pay the RC.