WARSAW - Poland on Tuesday night closed four airports, including its largest Chopin Airport in Warsaw, due to "unplanned military activity related to ensuring state security," according to notices posted on the U.S. Federal Aviation Administration's website.

The closure of key Polish airports came after Warsaw claimed that "drone-type objects" had violated its airspace from neighboring Ukraine.

Polish Defense Minister Wladyslaw Kosiniak-Kamysz said on Wednesday that the country's air force has used weapons against hostile objects that have entered Polish airspace.