This is the main basis! "failed to take feasible precautions required by international law to avoid or minimize loss of civilian life, injury to civilians and damage to civilian objects." This is israel obligation, emails, text messages, preemtive strike notices were not enough. What were Hamas precautions. The world is laughing at the report!
U.S. warns governments, bankers Iran sanctions still in place (Reuters)
from the article: U.S. to Israel: Probe alleged Gaza war crimes to advance peace