The short answer to your question is yes. The long answer is a bit more complicated but I'll explain.
Prior to December 7th, 1941, the Japanese had already had a long period of aggression in East Asia. While most Western countries scoffed at the Japanese, they were also all acutely aware that Japan had modernized, done so fast and with vigor, and in a span of half century from the fall of the Tokugawa Shogunate to the Russo-Japanese war, managed to make more strides economically and militarily than pretty much any other country in the war, which was highlighted by the decisive Russian defeat in the Russo-Japanese war. Western nations noticed and a lot of the time they went out of their way to ensure that the Japanese were frustrated in their territorial gains and advancements in the area.
Now speaking towards the 10 year window before, Japan had continued expanding even while the rest of the world was recovering from the Great Depression. This was mostly into China, and they had established a puppet regime in Manchuria and conquered Korea. While the war with the Chinese factions began in earnest again after the Marco Polo Bridge Incident in 1937, they had fought numerous border conflicts. After the infamous "Rape of Nanking," most of the rest of the world was on high alert. The United States was also extremely disturbed by the Japanese actions, and despite the Japanese losing handily to the Soviet Union during a border skirmish, the fact that the US occupied the Philippines was so close to the areas of interest for Japan, the U.S. was very much threatened by these actions. That is a big reason for the US embargo of goods to Japan during the late 1930s. And an embargo also shows that a country is generally threatened by whoever they are embargoing. It should also be noted that Japan also declared war on the Western Allies prior to attacking the U.S, which further increased American fear of any Japanese threat since many of those possessions lay on the opposite side of American held territory.
Now, did the United States fear an impending attack on the continent or Hawaii? Not really. They did move their Pacific Fleet closer to the Japanese isles, which shows some degree of concern. The United States simply feared for it's Pacific possessions more so than they did about an attack on the mainland or any serious conflict that would result in the total war that WWII turned out to be. However, most people considered that the two countries were on a crash course with each other during the time at some point, so the threat was there.
So, here comes the more difficult bit to interpret. Was the U.S. ever really in danger of a mainland invasion/war in which the Japanese would win? Well, this is very subjective. It is my OPINION that no, that was never the case. Looking at Japanese plans for the war, what they really wanted was to secure all valuable resources in Asia, and then fight a war of attrition against the Americans far from Japan on remote islands and in the Pacific Ocean proper. They never truly thought they could defeat the US. What they wanted was to take the European possessions and then stall long enough that America would simply give up. They never seriously wanted to threaten the US mainland, only the Asian sphere, and since most of American economy and power was not in Asia, they did not think that the U.S. would be as committed as they were after a few years of grinding through islands, and they had hoped that Pearl Harbor would simply give them time. Their war plan was very defensive minded after the initial advances, unlike the German war plans, and so from the start they were never going to cause a huge problem for Americans in North America. That is simply an opinion though.
So to summarize. Yes, the US was threatened by the Japanese Empire, mostly out of fear for it's colonies in the area and not for the welfare of the mainland. It embargoed them and sent supplies to their enemies in the hope of staving off any sort of attack in the area without fighting, but that fact alone shows some sort of threatened attitude. Japan was at war long before Germany ever even got started, and many scholars believe that World War II was in fact started by the Japanese and not the Germans in the sense of it being a global conflict.