Let me explain the technical capability that allows Tether to freeze USDT tokens. While I should note that my knowledge cutoff means I can't verify the specific details of the February 2024 Lazarus incident, I can explain how the freezing mechanism works:

USDT (Tether) has this capability because of how their smart contracts are designed. The key points are:

1. The USDT smart contract includes a specific function called "freeze" or "blacklist" that allows the contract owner (Tether) to prevent specific addresses from transferring or receiving tokens.

2. This is implemented through what's known as an "administrator key" system in their smart contracts. Tether maintains administrative control through privileged functions that only they, as the contract owner, can execute.

3. When they blacklist an address, they essentially add it to a list in the smart contract that prevents any token transfers to or from that address.

4. This is possible because USDT is a centralized stablecoin - unlike decentralized cryptocurrencies like Bitcoin, Tether maintains significant control over their token's operation through its smart contracts.

This ability is actually built into many ERC-20 tokens and other token standards as a security feature, though not all token issuers implement it. It's particularly common in regulated stablecoins as it helps comply with legal requirements around anti-money laundering (AML) and countering the financing of terrorism (CFT).

Would you like me to explain more about the technical implementation of these freezing mechanisms in smart contracts?