Up to 25 small hot-air balloons, some confirmed to be carrying smuggled cigarettes, entered Lithuanian airspace late Saturday, forcing authorities to close Vilnius Airport for several hours, officials said Sunday.

The incident disrupted around 30 flights and affected some 6,000 passengers before operations resumed at 4:50 a.m. local time, according to Lithuania’s National Crisis Management Center.

Border police later recovered 11 of the balloons and seized nearly 18,000 packs of smuggled cigarettes in various locations across Vilnius County, said Darius Buta, a spokesperson for the border service.

Two of the balloons reportedly flew directly over the capital’s airport, while others reached areas surrounding the city between 8:45 p.m. Saturday and 4:30 a.m. Sunday.

Authorities said the balloons originated from Belarus and were used by smugglers to ferry cigarettes into the European Union — a growing trend as such balloons are cheaper than drones.

The intrusion came amid heightened security concerns in the Baltics, following recent airspace violations that some NATO officials suspect were tests by Moscow to gauge the alliance’s response.

Lithuania, which borders Russian ally Belarus, has already faced several drone incursions this year, including one carrying an explosive device that crashed at a military training ground in July. In response, the Lithuanian parliament authorized the armed forces to shoot down any unmanned aircraft violating its airspace.

“Both smuggling balloons and drones are criminal activities, but not provocations or acts of sabotage,” Buta said, noting that similar incidents were also reported in August.

Last year, Lithuanian authorities intercepted 966 smuggling balloons from Belarus, compared to 544 so far this year.