Long-standing border disputes and political turmoil in Iran prompt Iraqi President Saddam Hussein to launch an invasion of Iran's oil-producing province of Khuzestan. After initial advances, the Iraqi offense was repulsed. In 1982, Iraq voluntarily withdrew and sought a peace agreement, but the Ayatollah Khomeini renewed fighting. Stalemates and the deaths of thousands of young Iranian conscripts in Iraq followed. Population centers in both countries were bombed, and Iraq employed chemical weapons. In the Persian Gulf, a tanker war curtailed shipping and increased oil prices. In 1988, Iran agreed to a cease-fire.