Get under there and yank on them and try to push the unions apart with your hands or small prybar. The nut and taper will not likely move, but if the taper shaft comes out of the socket to any noticeable degree you have a worn arm which needs replaced.
I can't find if you mentioned the year, but the gen 1 HMMWVs have a known weak steering. Very easy to yank the idler arm out of its socket, in my case... Hummer Parts Guy has the official patch, new stronger pitman and idler, or one can upgrade the entire linkage to A1/H1. I'm leaning towards the latter, once I raise funds.
Bulldogger