Foreign holders of Russia's sovereign bond maturing in 2029 are watching as the latest debt payment from the sanctioned nation draws closer to completion.

The $66 million coupon due March 21 was processed Tuesday by Russia's National Settlement Depository (NSD), it said in a statement. Earlier in the day, the Finance Ministry said it had transferred the cash to the NSD, thus meeting its obligations "in full." Four bondholders in Europe said they hadn't received the payment as of 3:40 p.m. in London.

From this point, the cash would typically journey to custodian banks, which hold assets for safekeeping, and then on to bondholders' accounts. But given the sweeping sanctions in place against Russia following President Vladimir Putin's invasion of Ukraine, concerns will remain until the money actually lands in investors' accounts.