The sale could complicate Russia 's mediating role in Iran 's nuclear standoff with the United States and Europe , a role that recently received the backing of the United States .
Europe /location/location/contains Russia
DT NN MD VB NNP POS VBG NN IN NNP POS JJ NN IN DT NNP NNPS CC NNP , DT NN WDT RB VBD DT NN IN DT NNP NNPS .
Europe
LOCATION
Russia
LOCATION
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