BEIRUT — The roadblocks and sandbags are back, cafes and hotels are nearly empty and many of the tourists are gone.Anxiety is gripping Lebanon following a spate of suicide bombings, and an ongoing security sweep targeting militants — some of them who had been staying in four-star Beirut hotels — has triggered a wave of cancellations of hotel and flight bookings in a country already on edge.The militants involved are said by security officials to be part of a network of alleged terrorist sleeper cells planning suicide bombings targeting security leaders and civilians alike. That has fueled concerns that Sunni extremists surging in Iraq and Syria were taking their fight to Lebanon next.Along Beirut's Mediterranean corniche, crowds are thinner. Not far away is the seaside Duroy hotel — one side of it still slightly blackened after a suicide bomber blew himself up during a police raid on his room on June 25. At the high-end Beirut Souks shopping complex in the downtown business district, the passages between shops are nearly empty of shoppers."In the month or two before the incident at the Duroy, we were seeing a lot of Saudi, Iraqi tourists," said a 36-year-old bookstore manager in downtown Beirut. "We really thought that the start of this summer was better than the last one.""Then the bombings and arrests happened, and we didn't see them anymore," she added, asking to remain anonymous because she was not authorized by her employer to speak to journalists.Lebanon, a tiny country with a history of civil strife, has been profoundly affected by the civil war raging in neighboring Syria over the past three years. In addition to the influx of well over 1 million Syrian refugees to the country, the conflict has inflamed tensions among Lebanon's long-feuding sects, causing violence, including street clashes and bombings.The country is sharply split between those who back the overwhelmingly Sunni rebels fighting to topple Syrian President Bashar Assad, and those who support him, including the Shiite militant group Hezbollah, which has sent its fighters to shore up Assad's forces against the rebels.The recent cancellations cap a downward trend in the number of tourists to Lebanon since the conflict in Syria began. Tourism Minister Michel Pharaon said the number of tourists in 2013 dropped by 1 million compared to the 2.3 million tourists who visited Lebanon in 2010. The number of visitors for the first five months of 2014 was down 9 percent from the same period last year, though the ministry had no figures for June and July.After enjoying relative calm for nearly three months, a new wave of violence erupted in the middle of last month, coinciding with dramatic events in nearby Iraq, where militants of the al-Qaida splinter group called the Islamic State have taken over large parts of the country. In the space of one week beginning June 20, a suicide attacker blew up his car near a checkpoint in eastern Lebanon, another near a cafe in southern Beirut and a third blew himself up at the Duroy to avoid arrest.The explosions killed two people and wounded others. Security forces searching for the militants have raided several hotels in Beirut, upsetting tourists, some of whom headed to the airport immediately afterward. A military prosecutor on Monday charged 28 people with planning bombing attacks and belonging to the Islamic State group.Now, instead of the relatively calm summer that Lebanese had hoped would bring some badly needed cash for the economy, workers put up roadblocks to guard against car bombs. Guards at malls search shoppers more meticulously. At the World Cup Fan Park in Beirut, organizers erected metal detectors at two entrances to the open air complex with three giant screens. Additional security personnel go through personal belongings before allowing fans to enter.Pharaon said Lebanon's security situation is better than other countries in the region. But, he said, if there is a militant "insistence to target Lebanon, this will impact not just on the tourism sector but the overall situation in Lebanon."Ayman Fariq Abu Ali, a 30-year-old taxi driver, says his worry is not possible new violence — "We grew up with death. We're used to it," he said. He's more concerned with making a living with tourists gone. In previous years, he had long-distance fares with tourists visiting around the country. Now he waits on the sidewalk for small fares, sweating in the thick heat.Following the attacks, the United Arab Emirates reissued a warning to its nationals not to travel to or stay in Lebanon, making business owners fear that other Gulf states will follow suit."This is going to impact Gulf tourism in Lebanon. If I'm from the Gulf, why would I want to go to a country where every day there is an explosion or a car bombing?" asked George Alam, a political analyst.