Warships are expensive to fuel and maintain, hard to construct and in very limited supply. According to fleet-in-being, limited naval operations should be conducted in preparation for a possible future decisive engagement. Smaller ships are better at this role, though cruisers, battleships and even carriers can also engage in solitary operations with sufficient speed. The most common form of naval engagement is that between small patrol boats, corvettes, frigates or destroyers, alongside standoff attacks or raids from these kinds of ships against capital ones or installations. Submarines also excel at these types of operations.