Without more information, if I had to guess:
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https://www.controlrisks.com/our-thinking/insights/greece-taking-on-the-anarchists
Since 2018, another anarchist group, Rouvikonas (Rubicon), has been active in carrying out attacks. It has targeted lawyers and judges involved in the sale of foreclosed properties, as well as diplomatic buildings, charities implicated in scandals, and banks – occasionally blowing up automated teller machines (ATMs). The group has also turned its attention to the activities of multinational companies operating in Greece.
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https://greekreporter.com/2019/01/07/anarchists-throw-paint-at-u-s-embassy-in-athens/
Later, Rouvikonas claimed responsibility for the attack on an anti-establishment website.
The claim condemns “American imperialism”, and in particular to the role of the U.S. via the International Monetary Fund, and the situation in Syria.
NOVEMBER 2, 2023
Greek Anarchists Display Solidarity with Palestinians by Unveiling Banner at Israeli Embassy
by GCT
Good catch. Could be