A capitalist country is not a pacifist, and neither is it an aggressor (initiator), but it will defend itself.
“Isolationist” is a smear term, used against countries that don’t wish to interfere in other countries. If the country does interfere it is called “Imperialist”.
“Peace, commerce, and honest friendship with all nations-entangling alliances with none.”
Under capitalism, the army is made up of volunteers.