Yes, Russia is a military threat to the United States, because both countries want to be world super powers. Things have not changed since the Cold War. The two countries have very different views on capitalism, communism, and which is the preferred economic system. Russia will go as far as it can until the United States responds.
The buzzing of a jet from Russia on an American jet has sparked debate once more (alongside the issues continuing in the Ukraine and smoldering issues from the Cold War's remnants) among Americans and Russians alike. The jet itself is a threat to its pilot and people on the ground in its ability to cause damage. Countries as an entity are a threat to one another in their propensity to require resources or feel threatened by ideologies and/or power and wealth from other nations. Whether or not it is Russia or another country, all nations pose a potential threat in some form to the United States, but the reality of whether or not we should react to such threats in the light of a simple buzzing of two jets (this was not nearly the incident it could have been, after all) should be cautiously considered. This also means that when we permanently label what might in the subconscious consistently be a threat, is just as serious and should not be done lightly. Could Russia do damage to the United States in some form? Absolutely, but labeling it a 'threat' just because of one jet can be detrimental to the relationships not merely between our two nations, but to the world in general.
I do not believe that their military is any where close to as strong or as large as the United States military is, but that does not mean that if we got into a war with Russia that it would be won easily and without tremendous loss of life. Keeping open lines of communication with Russia is pertinent so that we never have to face that threat.
Russia is a large threat to The United States of America. Russia holds the most number of Nuclear War Heads in the whole World, It can turn The United States Of America into ashes in any second, plus the Russian Military are rested, unlike the U.S. Military who're tired of battle in Afghanistan and Iraq. The United States Military is not in shape to face the grandsons of the Red Army.
Russia really is not much of a military threat to the United States. There is half a world between the two countries, and for now Russia is focusing on other things, like trying to keep the country from falling apart. The United States could easily stand up to the Russian military.