The other risk is that one of the two countries may mistake the other's defensive build-up as preparation for aggression and take pre-emptive action against it.
That expectation may make them more defensive and more likely to respond with aggression themselves, as we saw in this study and in other studies we have conducted.
However, it was just to take care of a nosebleed and the 6ft 6ins man from Tandil recovered sufficiently from a slow start to ensure an absorbing encounter which saw his aggression from the baseline up against Murray's defensive skills.