The Dutch intelligence service (AIVD) Thursday announced it uncovered a Russian spy attempting to infiltrate the International Criminal Court (ICC) through an internship program.

AIVD released a partially-redacted document explaining the man’s extensive cover story, in which he claimed to be Brazilian. According to AIVD:

The Russian intelligence officer purported to be Brazilian citizen Viktor Muller Ferreira (born on 4 April 1989), when in fact his real name is Sergey Vladimirovich Cherkasov (born 11 September 1985). Cherkasov used a well-constructed cover identity by which he concealed all his ties with Russia in general, and the GRU in particular.

AIVD labeled Cherkasov a “potentially very high threat,” one of the highest security threat labels. AIVD defended the label, saying: “If the intelligence officer had succeeded in gaining access as an intern to the ICC, he would have been able to gather intelligence there and to look for (or recruit) sources, and arrange to have access to the ICC’s digital systems.”

AIVD also reported Cherkasov to the ICC and deported him back to Brazil.

Russia and Brazil have yet to comment. The ICC said in a statement that it was “briefed by the Dutch authorities and is very thankful to the Netherlands for this important operation and more generally, for exposing security threats.”