Which directly led to the first armed conflict between Arabs and Israelis?

The 1948 Arab-Israeli War was the first in a series of war of attacks directed against the State of Israel from its Arab neighbors.

The war began with a united Arab attack on the day after the Israeli Declaration of Independence, on May 14, 1948. The fighting took place mainly on the territory of the former British Palestine Mandate, but also on the Sinai Peninsula and southern Lebanon. The war did not end with a peace treaty, but only with a ceasefire in 1949.

Palestinian territories started following the UN deceleration in 1947.