How to alleviate tension when interacting with researchers at a conference from enemy countries? In academic conferences, I often meet students and professors from enemy countries, whom I could never have met in normal situations. We both know that we are here for research, and we do talk about research, but there is still tension in the air. Maybe even mutual fear. What can I do to alleviate the tension, so that we can focus on the research?
There has long been a link between scientific collaboration and diplomacy between countries.  During some of the deepest parts of the cold war, for example, the United States and the Soviet Union worked together to stamp out polio, and the echoes of "vaccine diplomacy" continue today, uniting people against their common non-human enemies.  Even when there is not an explicit cooperative goal of that sort, contacts in a neutral situation can be valuable for helping to promote peace and understanding between different cultures and countries.

I would thus suggest beginning to approach the question not from a perspective of "Who is my enemy?" but from a question of "What are the areas that we can cooperate, even if we are enemies?" and perhaps to read up on ideas in "science diplomacy."