the Baghdad Pact. However, the overthrow of the Hashemites in Iraq in 1958 brought a nationalist government to power which promptly abandoned the pact. On 18 December 1959, Iraq's new leader, General Abd al-Karim Qasim, declared: "We do not wish to refer to the history of Arab tribes residing in al-Ahwaz and Mohammareh [Khorramshahr]. The Ottomans handed over Mohammareh, which was part of Iraqi territory, to Iran." The Iraqi government's dissatisfaction with Iran's possession of the oil-rich Khuzestan Province, which the Iraqis called Arabistan and had a large Arabic-speaking population, was not limited to rhetorical statements. Iraq began supporting secessionist movements in Khuzestan, and raised the issue of its territorial claims at an Arab League meeting, though unsuccessfully. Iraq showed reluctance in fulfilling existing agreements with Iran—especially after Egyptian President Gamal Abdel Nasser's death in 1970 and the Iraqi Ba'ath Party's rise which took power in a 1968 coup, leading Iraq to take on the self-appointed role of "leader of the Arab world". At the same time, by the late 1960s, the build-up of Iranian power under Shah Mohammad Reza Pahlavi, who had gone on a military spending spree, led Iran to take a more assertive stance in the region. In April 1969, Iran abrogated the 1937 treaty over the Shatt al-Arab, and as such, ceased paying tolls to Iraq when its ships used the waterway. The Shah justified his move by arguing that almost all river borders around the world ran along the thalweg, and by claiming that because most of the ships that used the waterway were Iranian, the 1937 treaty was unfair to Iran. Iraq threatened war over the Iranian move, but when, on 24 April 1969, an Iranian tanker escorted by Iranian warships sailed down the river, Iraq—being the militarily weaker state—did nothing. (Joint Operation Arvand) Iran's abrogation of the treaty marked the beginning of a period of acute Iraqi-Iranian tension that was to last until the 1975 Algiers Agreement. In 1969, Saddam Hussein, Iraq's deputy prime minister, stated: "Iraq's dispute with Iran is in connection with Khuzestan, which is part of Iraq's soil and was annexed to Iran during foreign rule." Soon, Iraqi radio stations began exclusively broadcasting into "Arabistan", encouraging Arabs living in Iran and even Baloch people to revolt against the Shah's government. Basra TV stations began showing Iran's Khuzestan province as part of Iraq's new province of "Nāṣiriyyah" (), renaming all of