If Turkish security authorities needed a reminder of the challenge posed by Pope Benedict XVI's visit to Turkey this week, Ibrahim Ak delivered it when he fired a pistol outside the Italian consulate in Istanbul and shouted that he wanted to strangle the pope with his bare hands.

"God willing, this will be a spark, a starter for Muslims ... God willing, he will not come. If he comes, he will see what will happen to him," the 26-year-old Turk told the TV cameras as he was led away in handcuffs.

The Nov. 2 incident ended without injuries, and nothing like it has happened since, but authorities are braced for trouble and have mobilized an army of snipers, bomb disposal experts and riot police, as well as navy commandos to patrol the Bosporus Straits flowing through Istanbul.

Benedict's four-day visit to this overwhelmingly Muslim nation begins Tuesday under the shadow of his September speech in which he quoted a Byzantine emperor who characterized some of the teachings of the Prophet Muhammad as "evil and inhuman," particularly "his command to spread by the sword the faith."

Like the rest of the Islamic world, many in this 99 percent Muslim nation are angry and want a fuller apology than Benedict's statement of regret for having caused offense.

Predicting big street protests, authorities plan to close several areas of Istanbul to traffic and are preparing lists of residents living in those neighborhoods.

Felicity, a pro-Islamic opposition party, is calling for a massive protest in Istanbul Sunday, before the pope arrives.

"If this trip would have occurred under normal conditions, then these lands, the center of tolerance and love, would show the necessary hospitality to him," it said in a statement. "But we don't want to see him on our soil because of the remarks he made about Islam's Prophet Muhammad on Sept. 12 and for not apologizing afterward."

Benedict will visit Istanbul, Izmir and Ankara, the capital. Istanbul, when it was named Constantinople, was the capital of Byzantine-era Christianity, but Christians are a tiny minority in modern Turkey, feel deprived of their rights and are expected to urge the pope to come to their defense.

There's also a shocking real-life event that ties Turkey to the Vatican — the shooting of Pope John Paul II in Rome by a Turk, Mehmet Ali Agca, for reasons that remain murky but have not been linked to Islamic issues.

That was 25 years ago, and Turkey today is striving to show the world it is a modern nation ready to join the European Union.

Turkish security forces have had ample experience in protecting world leaders, including Presidents Bush and Clinton. The military is powerful, publicly venerated and highly trained.

Still, senior anti-terrorism police officials, speaking on condition of anonymity because of the sensitivity of the information, said they worry that some anti-pope protests could turn violent.

Several radical Islamic groups are active, some with links to al-Qaida. A wave of suicide bombings against synagogues and British interests in Istanbul three years ago killed 58 people, and about 70 alleged al-Qaida operatives are on trial for the attacks.

Bin Laden's deputy, Ayman al-Zawahri, has compared Benedict to Pope Urban II, who in 1095 ordered the First Crusade to recapture the Holy Land from the Muslims.

On Feb. 5 a Turkish teenager shot dead a Catholic priest, Rev. Andrea Santoro, as he knelt in prayer inside his church in the Turkish port city of Trabzon. Two other Catholic clerics in Turkey were later assaulted.

Those attacks were believed related to widespread anger in the Islamic world over the publication in European newspapers of caricatures of Muhammad.

A recent Turkish thriller, "Plot Against the Pope" by Yucel Kaya carries the subtitle "Who will kill the pope in Istanbul?" Its conspiracy theory ties the assassination into a plot by conservative Roman Catholics, Freemasons and U.S. intelligence services to attack Iran, Turkey's eastern neighbor.