Scientists from both sides of the Iron Curtain met in Geneva in 1958 and 1959 to create the technical basis for monitoring a future nuclear test ban treaty. Despite their scientific veneer, these meetings were politically motivated and the scientists tried to forward U.S. or Soviet objectives through their technical discussions. Seismographic data was a cornerstone of the proposed monitoring regime, but when the discussions became political, so too did the instruments that produced the scientific data. Thus, seismographs became diplomatic (...) objects used to support or challenge foreign policy objectives. After the collapse of the scientific meetings, the US distributed seismographs as diplomatic gifts to create a worldwide, U.S.-controlled nuclear-detection network in 1960. To exploit data from the network without supporting U.S. policy objectives, the USSR in 1961 proposed to exchange U.S. seismographs for Soviet ones, as two objects of equal value. That allowed each superpower to access the other's technology without creating bonds of mutual obligations. However, this type of inverted, object-based diplomacy also gave scientists from international scientific organisations or small, non-nuclear nations like Denmark a way to engage in nuclear diplomacy. When Danish scientists offered to create a connection station between the U.S. and Soviet seismic networks, they did so in full agreement with the Danish Ministry of Foreign Affairs in order to strengthen their policy of nuclear disarmament independently of U.S. objectives. (shrink)