TAIPEI: As an election in democratic Taiwan looms, Chinese balloons have appeared around the island at various times of day in what its military says is a new form of 'grey zone' harassment.China already flexes its military prowess against self-ruled Taiwan daily, sending fighter jets, reconnaissance drones and naval ships around the island.But since December, Taiwan's defense ministry has said that mysterious balloons have crossed the narrow Taiwan Strait separating the island from China in a kind of 'grey zone' harassment.'Grey zone' tactics are aggressive actions deployed by a state that stops short of open warfare. Experts say that is what China has been doing with its show of military force around the island.Days before a presidential election, some balloons have flown directly above Taiwan, with at least one detected around a military airbase.'Beijing is signaling that it can violate Taiwanese airspace at will and challenge its sovereignty,' said Raymond Kuo, Taiwan Policy Initiative director at RAND Corporation.Self-ruled Taiwan is claimed by China as part of its territory, with Beijing's leadership vowing to bring the island under its control.The January 13 election pits frontrunner Lai Ching-te -- whose ruling Democratic Progressive Party says Taiwan is a sovereign nation -- against two others who have pledged warmer relationships with Beijing.The timing of the balloons' appearance is 'political,' said Kuo.'The CCP (Chinese Communist Party) is attempting to demoralize the Taiwanese public in the run-up to next week's presidential and legislative elections,' he told Agence France-Presse.But its military purpose is 'in line with broader China's grey zone coercion strategy towards Taiwan'.'Beijing is adding yet another operational challenge to Taiwan's defense forces, which could erode readiness and resilience,' he said.After initially saying they were weather balloons, Taipei's defense ministry on Saturday called them 'an attempt to use cognitive warfare to affect the morale of our people'.It also said they posed a 'serious threat' to aviation routes.When asked about the balloons, China's defense ministry dismissed allegations of interference and accused Taiwan of trying to 'manipulate the election.'Balloons from China became a politically fraught topic last February, when the United States shot down what it called a spy balloon. Beijing has said it was a civilian airship blown off-course.More than 20 balloons have crossed the sensitive median line separating China from Taiwan since December, with at least seven of them passing directly over the island.Sighted during the daytime and evenings, they move at altitudes ranging from 12,000 to 36,000 feet (3.6 to 11 kilometers), according to Taipei's defense ministry.