diff --git a/examples/long-running-process/index.js b/examples/long-running-process/index.js
index c7d04e361..71ab42b81 100644
--- a/examples/long-running-process/index.js
+++ b/examples/long-running-process/index.js
@@ -31,14 +31,17 @@ function update(process) {
             break;
         case ProcessState.STOPPED:
             run_button.removeAttribute("disabled");
+            run_button.innerHTML = "Start";
             break;
         case ProcessState.RUNNING:
-            run_button.setAttribute("disabled", "");
+            run_button.removeAttribute("disabled");
+            run_button.innerHTML = "Terminate";
             // StateChangeTimestamp property is in µs since epoch, but journalctl expects seconds
             showJournal(process.serviceName, "--since=@" + Math.floor(process.startTimestamp / 1000000));
             break;
         case ProcessState.FAILED:
             run_button.setAttribute("disabled", "");
+            run_button.innerHTML = "Start";
             // Show the whole journal of this boot
             showJournal(process.serviceName, "--boot");
             break;
@@ -69,10 +72,13 @@ cockpit.transport.wait(() => {
      * This runs as root, thus will be shared with all privileged Cockpit sessions.
      */
     run_button.addEventListener("click", () => {
-        process.run(["/bin/sh", "-ec", command.value])
-                .catch(ex => {
-                    state.innerHTML = "Error: " + ex.toString();
-                    run_button.setAttribute("disabled", "");
-                });
+        if (process.state === ProcessState.RUNNING)
+            process.terminate();
+        else
+            process.run(["/bin/sh", "-ec", command.value])
+                    .catch(ex => {
+                        state.innerHTML = "Error: " + ex.toString();
+                        run_button.setAttribute("disabled", "");
+                    });
     });
 });
diff --git a/pkg/lib/long-running-process.js b/pkg/lib/long-running-process.js
index 5be9ec6c9..0b68a6064 100644
--- a/pkg/lib/long-running-process.js
+++ b/pkg/lib/long-running-process.js
@@ -49,12 +49,12 @@ export class LongRunningProcess {
      *                 argument is `this` LongRunningProcess instance.
      */
     constructor(serviceName, updateCallback) {
-        // don't require superuser; this is only for reading the current state
-        this.systemdClient = cockpit.dbus("org.freedesktop.systemd1");
+        this.systemdClient = cockpit.dbus("org.freedesktop.systemd1", { superuser: "require" });
         this.serviceName = serviceName;
         this.updateCallback = updateCallback;
         this._setState(ProcessState.INIT);
         this.startTimestamp = null; // µs since epoch
+        this.terminated = false;
 
         // Watch for start event of the service
         this.systemdClient.subscribe({ interface: I_SD_MGR, member: "JobNew" }, (path, iface, signal, args) => {
@@ -79,6 +79,18 @@ export class LongRunningProcess {
                              { superuser: "require", err: "message", ...options });
     }
 
+    /*  Stop long-running process while it is RUNNING, or reset a FAILED one */
+    terminate() {
+        if (this.state !== ProcessState.RUNNING && this.state !== ProcessState.FAILED)
+            throw new Error(`cannot terminate LongRunningProcess in state ${ this.sate }`);
+
+        /* This sends a SIGTERM to the unit, causing it to go into "failed" state. This would not
+         * happen with `systemd-run -p SuccessExitStatus=0`, but that does not yet work on older
+         * OSes with systemd ≤ 241 So let checkState() know that a failure is due to termination. */
+        this.terminated = true;
+        return this.systemdClient.call(O_SD_OBJ, I_SD_MGR, "StopUnit", [this.serviceName, "replace"], { type: "ss" });
+    }
+
     /*
      * below are internal private methods
      */
@@ -88,6 +100,7 @@ export class LongRunningProcess {
         if (state === this.state)
             return;
         this.state = state;
+        this.terminated = false;
         if (this.updateCallback)
             this.updateCallback(this);
     }
@@ -100,7 +113,12 @@ export class LongRunningProcess {
                 break;
             case 'failed':
                 this.startTimestamp = null; // TODO: can we derive this from InvocationID?
-                this._setState(ProcessState.FAILED);
+                if (this.terminated) {
+                    /* terminating causes failure; reset that and do not announce it as failed */
+                    this.systemdClient.call(O_SD_OBJ, I_SD_MGR, "ResetFailedUnit", [this.serviceName], { type: "s" })
+                } else {
+                    this._setState(ProcessState.FAILED);
+                }
                 break;
             case 'inactive':
                 this._setState(ProcessState.STOPPED);
diff --git a/test/verify/check-examples b/test/verify/check-examples
index bd1f99f5a..49af2f0c7 100755
--- a/test/verify/check-examples
+++ b/test/verify/check-examples
@@ -93,6 +93,7 @@ class TestLongRunning(MachineCase):
         # run a command that the test can control synchronously
         ack_file = self.vm_tmpdir + "/ack_a";
         b.set_val("#command", "date; echo STEP_A; until [ -e %s ]; do sleep 1; done; echo STEP_B; sleep 1; echo DONE" % ack_file)
+        b.wait_text("button#run", "Start")
         b.click("button#run")
 
         b.wait_text("#state", "cockpit-longrunning.service running")
@@ -104,6 +105,7 @@ class TestLongRunning(MachineCase):
         b.logout()
         b.login_and_go("/long-running-process")
         b.wait_text("#state", "cockpit-longrunning.service running")
+        b.wait_text("button#run", "Terminate")
         b.wait_in_text("#output", "\nSTEP_A\n")
         self.assertEqual(m.execute("systemctl is-active cockpit-longrunning.service || true").strip(), "activating")
 
@@ -120,6 +122,7 @@ class TestLongRunning(MachineCase):
         b.login_and_go("/long-running-process")
         b.wait_text("#state", "cockpit-longrunning.service stopped")
         b.wait_text("#output", "")
+        b.wait_text("button#run", "Start")
 
         # failing process
         m.execute("rm -f " + ack_file)
@@ -134,6 +137,7 @@ class TestLongRunning(MachineCase):
         self.assertNotIn("\nNOTME", out)
         # does not contain previous logs
         self.assertNotIn("STEP_B", out)
+        b.wait_text("button#run", "Start")
 
         # failing state gets picked up on page reconnect
         b.logout()
@@ -144,6 +148,25 @@ class TestLongRunning(MachineCase):
         self.assertIn("\nBREAK_A\n", out)
         self.assertNotIn("\nNOTME", out)
         b.wait_present("button#run:disabled")
+        b.wait_text("button#run", "Start")
+
+        # reset
+        m.execute("systemctl reset-failed cockpit-longrunning.service")
+        b.wait_text("#state", "cockpit-longrunning.service stopped")
+
+        # cancel long-running command
+        b.set_val("#command", "for i in $(seq 100); do echo LONG$i; sleep 1; done")
+        b.wait_text("button#run", "Start")
+        b.click("button#run")
+        b.wait_text("#state", "cockpit-longrunning.service running")
+        b.wait_text("button#run", "Terminate")
+        b.wait_in_text("#output", "\nLONG2\n")
+        b.click("button#run")
+        # terminates cleanly
+        b.wait_text("#state", "cockpit-longrunning.service stopped")
+        self.assertEqual(m.execute("systemctl is-active cockpit-longrunning.service || true").strip(), "inactive")
+        b.wait_in_text("#output", "\nLONG2\n")
+        self.assertNotIn("\nLONG30\n", b.text("#output"))
 
 
 if __name__ == '__main__':