Tenant terminated lease early: can I keep their Security Deposit?

[Roderick McCleary]

Hi - new Landlord here dealing with this situation for the first time. My tenants bought a house and terminated our Lease 4mos premature. I have their Security Deposit still (equivalent to 1 month's rent) and they have completely moved out of the unit as of 3/31. Due to COVID, I've had a hard time finding a new Tenant so now my Unit is vacant.

In the Lease we signed together, there is language that states: "if the Tenant moves out prior to the natural expiration of this lease, a re-rent levy of [equivalent to 1 month's rent] will be charged to the Tenant.".

Given these circumstances, am I legally allowed to tell the Tenant due to them breaking their lease early I will simply keep their Security Deposit? Any insight will be helpful as I want to communicate this to them today or tomorrow.