[Threshold Network: Attacker Attempted to Mint tBTC Without Collateral but Failed, Preventive Measures Taken] Threshold Network posted on the X platform that at 18:04 Beijing time on May 18, an attacker attempted to mint tBTC without depositing the underlying BTC but was unsuccessful. No invalid tBTC was generated, and user funds were not at risk. As a precaution, given the increased frequency of malicious activities across the crypto ecosystem, Optimistic Minting has been temporarily suspended. Minting is now conducted through the sweeping mechanism, extending the minting time from approximately 1.5 hours to about 6-7 hours. According to the introduction, the fundamental security model of tBTC relies on a decentralized signer network holding the underlying Bitcoin, with each native minting verified through provable Bitcoin SPV proofs.