The $5.9 million settlement that the U.S. government reached in May with a firm allegedly tied with a massive $230 million heist from the Russian Treasury may hang in the balance as the government moves to enforce the agreement.

Prevezon, which had been accused of taking $1.9 million from the treasury scheme, argues that it is not able to pay the settlement because the assets it intends to use to pay up are being held by the Dutch government.