Hopes for another decade of relative tranquillity were dashed with the escalation of Arab terrorist raids across the Egyptian and Jordanian borders, persistent Syrian artillery bombardment of agricultural settlements in northern Galilee and massive military build-ups by the neighboring Arab states. When Egypt again moved large numbers of troops into the Sinai desert (May 1967), ordered the UN peacekeeping forces (deployed since 1957) out of the area, reimposed the blockade of the Straits of Tiran and entered into a military alliance with Jordan, Israel found itself faced by hostile Arab armies on all fronts. As Egypt had violated the arrangements agreed upon following the 1956 Sinai Campaign, Israel invoked its inherent right of self-defense, launching a preemptive strike (5 June 1967) against Egypt in the south, followed by a counterattack against Jordan in the east and the routing of Syrian forces entrenched on the Golan Heights in the north.
At the end of six days of fighting, previous cease-fire lines were replaced by new ones, with Judea, Samaria, Gaza, the Sinai peninsula and the Golan Heights under Israel's control. As a result, the northern villages were freed from 19 years of recurrent Syrian shelling; the passage of Israeli and Israel-bound shipping through the Straits of Tiran was ensured; and Jerusalem, which had been divided under Israeli and Jordanian rule since 1949, was reunified under Israel's authority.