A surgical instrument, comprising: an end effector , comprising: an ultrasonic blade ; and a clamp arm movable relative to the ultrasonic blade to transition the end effector through different closure stages between an open configuration and a closed configuration to clamp tissue between the ultrasonic blade and the clamp arm ; a transducer configured to generate an ultrasonic energy output; a waveguide configured to transmit the ultrasonic energy output to the ultrasonic blade ; characterised by a sensor configured to transmit sensor signals indicative of the closure stages of the end effector ; and a control circuit configured to: receive the sensor signals; and select an operational mode from operational modes delivering different ultrasonic energy outputs from the transducer based on the received sensor signals, wherein the closure stages comprise an initial closure stage spanning an initial portion of the clamp arm range of motion up to a predetermined threshold, wherein the control circuit is configured to select a first operational mode delivering a first ultrasonic energy output in the initial closure stage, and wherein the control circuit is configured to switch to a second operational mode delivering a second ultrasonic energy output greater than the first ultrasonic energy output beyond the predetermined threshold. an end effector , comprising: an ultrasonic blade ; and a clamp arm movable relative to the ultrasonic blade to transition the end effector through different closure stages between an open configuration and a closed configuration to clamp tissue between the ultrasonic blade and the clamp arm ; an ultrasonic blade ; and a clamp arm movable relative to the ultrasonic blade to transition the end effector through different closure stages between an open configuration and a closed configuration to clamp tissue between the ultrasonic blade and the clamp arm ; a transducer configured to generate an ultrasonic energy output; a waveguide configured to transmit the ultrasonic energy output to the ultrasonic blade ; characterised by a sensor configured to transmit sensor signals indicative of the closure stages of the end effector ; and a control circuit configured to: receive the sensor signals; and select an operational mode from operational modes delivering different ultrasonic energy outputs from the transducer based on the received sensor signals, wherein the closure stages comprise an initial closure stage spanning an initial portion of the clamp arm range of motion up to a predetermined threshold, wherein the control circuit is configured to select a first operational mode delivering a first ultrasonic energy output in the initial closure stage, and wherein the control circuit is configured to switch to a second operational mode delivering a second ultrasonic energy output greater than the first ultrasonic energy output beyond the predetermined threshold. receive the sensor signals; and select an operational mode from operational modes delivering different ultrasonic energy outputs from the transducer based on the received sensor signals, wherein the closure stages comprise an initial closure stage spanning an initial portion of the clamp arm range of motion up to a predetermined threshold, wherein the control circuit is configured to select a first operational mode delivering a first ultrasonic energy output in the initial closure stage, and wherein the control circuit is configured to switch to a second operational mode delivering a second ultrasonic energy output greater than the first ultrasonic energy output beyond the predetermined threshold. <EOS>