During comments made at a forum organized by the foreign policy think-tank Incipe, the Spanish army's Chief of the General Staff Jaime Domínguez Buj stated the current situation in Catalonia "pained" him deeply.
He said such events usually happened when "central power is weak".
"When the metropolis is weak, the collapse comes," General Domínguez said during the controversial appearance in what he later said was a reference to the Spanish–American wars of independence at the start of the nineteenth century.
In the case of Catalonia, he argued force could only be used "stop" an independence drive in the region but could not "change" it.
"We have to win hearts and minds," and convince people it is better to stay Spanish", he was reported as saying by participants at Tuesday's event.
But the general reminded participants the army existed to "uphold the law and the Spanish constitution" and could be used "in whatever form" the government decided.
It "is prepared to intervene at home or abroad, to go to Afghanistan or Valencia," he said in quotes cited by Spanish daily El País.
Spain's major opposition party, the Socialists, were quick to react to the comments asking for a clarification with a parliamentary spokesperson calling them "deeply inadequate".
The left-wing IU party called the comments "crazy" while the ruling Popular Party's spokesperson Alfonso Alonso called them "difficult to understand".