The meaning and significance of the concept of thresholds stress intensity factor for environmentally assisted cracking (EAC), K_EAC, is revised. Focusing on the key item of the autonomy of the crack tip region in the case of EAC, the discussion is confined to small scale yielding, apparently well characterised in terms of the stress intensity factor K. Firstly, the manifestations of the experimental uncertainty of the evaluation of the threshold K_EAC are  briefly reviewed and a series of testing/service variables are found which can affect EAC in addition to K. An analysis of the matter K–dominance in EAC shows that this phenomenon is not intrinsically controlled solely by K. This calls for more restrictions to be imposed in EAC testing to ensure a reliable evaluation of EAC and thus to provide guidelines for engineering assessment of structural integrity.