ANKARA – A Turkish court has convicted 330 military officers — including the former air force and navy chiefs — of plotting to overthrow Prime Minister Recep Tayyip Erdogan's government in 2003. It says a panel of three judges at the court in the outskirts of Istanbul initially sentenced former air force chief Ibrahim Firtina, former navy chief Ozden Ornek and former army commander Cetin Dogan to life imprisonment but later reduced the sentence to a 20-year jail term. The three were accused of masterminding the plot. The court also convicted 327 other active or retired officers for involvement in the conspiracy, sentencing some to as much as 18 years in prison. Thirty-four were acquitted while the case against one was postponed for health reasons. The Turkish army has traditionally played a dominant role in politics, staging three coups between 1960 and 1980 and pushing the country's first Islamist-led government from office in 1997. Its authority has been reined in sharply since Erdogan first came to power nearly a decade ago and the trial has been seen as a show of strength by a government that has emerged from its shadow. The “Sledgehammer” conspiracy is alleged to have included plans to bomb historic mosques in Istanbul and trigger conflict with Greece to pave the way for an army takeover. Prosecutors had demanded 15-20 year jail sentences for the 365 defendants, 364 of them serving and retired officers. Meanwhile, Erdogan canceled a trip to the United States where he was due to attend a UN General Assembly meeting next week, an official from his office said, citing a forthcoming party congress and heavy work schedule. “Prime Minister Erdogan canceled his US trip because of the party congress on September 30th, as well as his busy schedule,” a source in his office said. Foreign Minister Ahmet Davutoglu will now lead the Turkish delegation at the New York meeting. – Agencies