Does the security deposit post to the blockchain?

Hi,

I am wondering where the bitcoin is stored for the security deposit. How do you get the BTC from an external wallet to Bisq for the security deposit? Obviously you could use the blockchain to transfer some to a bisq wallet first. Then what? Would it be two blockhain transaction to go from external wallet like mycelium to security deposit?

Security deposit is stored in the Bisq internal wallet until the trade starts. Then it is locked in the multisig with the other trader and the arbitrator.