Interventionism has become a term thrown around for any nation that gets involved in any war, suggesting warmongering, even in cases of smaller conflicts. Equally, non-interventionism is used by people to suggest that one avoids war in almost every case.
The terms themselves are styles more than acts, the intervention is by one who intervenes, thus any nation intervening is interventionist, and non-intervention is not doing as much, in the modern political environment such terms are made foggy, since most of us admit there are good and bad reasons for intervention, and in come cases to intervene is a must.
So in actuality, there are massively pro-war politicians, somewhat pro, somewhat against, and highly against even when we may be best of intervening in a disastrous period for a region, such as a civil war or to cast off a hazardous tyranny, or both. These options are made overly simple, into a binary system of warmongering vs. peace-loving, or pro-democracy vs. isolationism.
The trouble is who you listen to, who you accept as an authority, and thus, which biases you then hold on to, is it Fox News, The Young Turks, or another News, or News-like service?