Israel accepted the UN mandated partition but it was rejected by the Palestinians and all the Arab countries. Israel was then invaded by the armies of Syria, Iraq, Jordan, Egypt and Lebanon plus "irregular" Arab Palestinian forces and muslim volunteers from around the world. So yes, that pretty much meets the definition of defensive war.
U.S. and Russia discuss flight safety in Syria on conference call (Reuters)
from the article: Israeli population stands at 7,695,000 at end of 2010