Defendants in the US would be charged with racketeering, not bribery, since government officials were not bribed. The DoJ indictment against Webb et al. is here: most of the defendants are not citizens of the US, though none are listed as being government officials. DoJ could certainly seek an indictment of ministers, senators or presidents of foreign countries. If said official were in the US on an ordinary passport, they could be arrested. They also might be arrested by e.g. Argentinian policy and extradited to the US, but whether that would be legal depends on the country (some countries don't extradite their own citizens; there would have to be an extradition treaty between that country and the US). It is inconceivable that any nation would hand over a sitting president because of an indictment by the US, and generally unlikely for any government official, but the official could be locally deposed first. But whether a government would do this is basically a political question, not a legal one.