Democrats, particularly Obama, like to say they hate to use military and want to make it smaller. But this is not true, lets compare who has started more wars, the GOP or the Democratic party. Woodrow WIlson (Democrat progressive) entered WW1, FDR (Democrat liberal) entered WW2, and Truman (Democrat liberal) entered the Korean war. Lincoln (Republican liberal) entered the civil war, Eisenhower (Republican) entered Vietnam war, and George W Bush (Republican Conservative) entered the war on terror. As you can see both sides are about equal on this so it is not one-sided. I think that both sides do want military involvement to increase resources and influence, however, it depends on the circumstance that arises.
I don't see the logic to providing 30% of the entire world's military expenditures, but while we're unchallenged, let's allow our love of democracy and human equality to outweigh our fear of terrorism and our grasp on political establishment, and use our power as leverage for our principles rather than our principles as leverage for our power. Let's pursue a legacy of civilized and caring dominance, and attempt to pass the same humanistic expectations to the next dominant military force, rather than constantly working to maintain our empire status.
Democrats are well known for wanting less guns so it only makes sense that they would also like a smaller military, along with the facts that show we do not need such a large military and money goes to waste on unnecessary objects we are just wasting all our money on.
Democrats and Republicans have been long rivals, but have had radically different viewpoints throughout history. I think it would be more accurate to not label someone based on party, but on a left/right scale. Liberals have had a historical tendency to be averse to wars, however, their constant search to expand freedoms (Ending slavery, gay rights, woman's suffrage, things like that) usually leads them into conflict within their party. Syria, for example, is a wonderful one. Some might say "We have a duty to go help their people!" as is the generalized liberal view, but the anti-war part of their philosophy causes controversy. Conversely, Conservatives are all about remaining static. Their lack of wish to change, no matter the cost (such as their dislike and refusal to comply during the end of slavery, back when Democrats were conservatives) doesn't give them much care beyond what is within our country, but their ideals of economic expansion & general imperialistic viewpoints cause them to wage war more easily, and usually be the first to support the idea for resources (Iraq, for example, was purely for oil purposes) though they may purposely oppose such things if it agrees with the progressive agenda because it makes it more likely for change to occur (i.E. If Russia's anti-gay laws were in affect but they were weak militarily and had a vast amount of resources, conservatives would want to go there for the resources but despise it because it supports the liberal view and gives more leeway for change to occur).