This explains how the Ukrainian authorities were able to block the wallets. Decentralized blockchains, such as Bitcoin and Ethereum, do not allow anyone to block or freeze any addresses or transactions. However, centralized custodial exchanges, such as Binance, Coinbase (COIN), FTX, which hold cryptocurrency on their users’ behalf, can refuse service to individual users at the request of authorities.
Source: https://www.coindesk.com/layer2/sinweek/2022/08/31/binance-froze-russian-gun-makers-crypto-assets-likely-at-ukraines-request/?utm_medium=referral&utm_source=rss&utm_campaign=headlines