The original strategy for the ITER divertor in ITER research plan in 2008 was that the replacement of CFC/W divertor with all W divertor during D-phase after the demonstration of a 15MA H-mode integrated scenario with ELM amelioration. In 2009, in order to accelerate initial operation phases before DT-phase, baseline strategy was revised that ITER operation starts with CFC/W divertor and it changes out to full W divertor before the nuclear phase (D-phase) after the confirmation of the controllability of transient events in H/He phase. However, in the frame of the ITER cost containment policy, the option for implementing a single divertor up to achieving the Q=10 milestone in the nuclear phase has been proposed by ITER organization and supported by ITER council. Then, the ITPA Coordinating Committee has asked the ITPA groups to provide a scientific view on issues linked with the ITER divertor strategy for submission to ITER Science and Technology Advisory Committee held in May 2013. In ITPA "transport and confinement (T&C) topical group" and "pedestal and edge physics (PEP) topical group", joint session discussing ITER divertor strategy at autumn meeting held in San Diego, October 2012. In the session, influence of W divertor on the access to the H-mode, effect of W divertor on pedestal parameters and plasma confinement, predicted impacts of wall and divertor material on pedestal structure, requirements for ELM control to prevent W accumulation, transport of high Z impurities in the core plasma and possibilities for its control have been discussed. Based on this session, both groups have agreed to provide joint report based on the common understanding that no significant issue is identified in the T&C and PEP research area regarding the start of operations with a CFC/W divertor. In this report, therefore, the evaluation has focused on the additional risks associated with the start of ITER operation up to the DT phase with a single W divertor, and has been structured in the following five topics: 1. Operation in L-mode (C. Angioni, M. Reinke) 2. Access to H-mode (J.W. Hughes, F. Ryter, C. Maggi) 3. Operation in H-mode (T. Pütterich, C. Angioni, R. Dux, V. Bobkov) 4. Quality of H-mode plasmas (M. Beurskens, J. Schweinzer, F. Ryter, M. Reinke) 5. Specific issues in He plasma operation (M. Reinke, C. Angioni, F. Ryter)