Jonathan Kent is an agent with the Counterespionage Service.
American Espionage Service is the name of the organization that he mentions when he is shown applying for a job with them in Washington approximately a year after the end of World War II. By the third recorded adventure, however, he is clearly shown to be employed by the Counterespionage Service. Whether the original department changed its name, which is not unheard of, or Kent moved from one department of Intelligence to another. It is for the CS that he says he work for on subsequent cases.
When asked why he wanted to become a secret operative, Kent recounted his early years and the impressions they made on him. His father had been an American engineer hired by "a foreign government during an early five-year plan". Young Kent, then about 10 years old, accompanied his father and saw the oppression that was rampant in that nation; men and women "beaten, jailed and shot for speaking their minds". As he grew older he saw "the Red Army, master of a groaning nation" and the tyranny it imposed.
Later when WWII began and Kent joined the American military, he not only achieve an impressive record as a fighter pilot, he was also on hand when the concentration camp at Buchenwald was freed and he not only saw the evils of the Nazi regime, he saw the total disregard for the suffering by the Russian soldiers who aided in freeing it. It cemented in him the desire to do something about both.
Kent is now in his late 20s or very early 30s. He is good looking with brown hair and a quick smile though that can turn into a scowl easily enough. He is broad-shouldered and obviously athletic based on the actions he is seen doing; he seems especially found of climbing. He is an excellent shot with a hand gun and shows no hesitation to popping off a shot or two. His hand-to-hand fighting skills are also impressive though from the recounts he has an unfortunate habit of being hit from behind a lot.
While Kent does not appear to have a steady relationship, hard to do with his constant travel for work, he is most definitely fond of the fairer sex and based on their actions the feelings are returned. He receives more than one kiss from ladies he deals with though he has the not uncommon for that era chauvinistic tendency to call them 'honey' and 'baby'. In one randomly selected adventure he referred to the female he was working with by name three times and by 'honey' four times, 'baby' twice, 'sweetheart' twice, and 'sugar-puss' once.
Silly speculation: We first meet the agent Jonathan Kent in August 1949. In February of the next year, DC Comics reveals the first name of Pa Kent who, along with his wife, Martha, found and adopted Kal-El when he arrived on Earth as a baby in a spaceship from Krypton and raise him to be Superman. It was Jonathan. Are they the same man? Unlikely because one is a Kansas farmer and the other a big-city spy hunter. Still ...