Excuse me for necroing the post, but I had a similar (almost the same) situation, BUD-HEL-DFW-MSP, all AY marketed and last one operated by AA
HEL-DFW arrived earlier, however DFW immigration and security was a zoo, so I missed my connection and arrived more than 4h later to MSP.
Just wanted to confirm that I am amble to claim EC261 compensation and looking at this topic I should be contacting AA for the said compensation.