Analyze the relationship between 'Syriza' and 'ATHENS' within the context of the input sentence.
Options: headquarters location, legal form, operator, product/material produced

ATHENS - Greek Prime Minister Alexis Tsipras, struggling to contain a revolt in his left-wing Syriza party, said on Wednesday that his government would not implement reform measures beyond those agreed with lenders at a euro zone summit this month.
headquarters location