Ukrainian defense attache had been summoned to the country's Ministry of Defense over allegations that a Ukrainian helicopter had entered Belarusian airspace, Belarus said on Sunday.

Belarus lodged a formal protest and alleged that a Ukrainian military helicopter flew one kilometer (0.6 miles) Saturday into Belarusian territory, officials said.

But Ukraine immediately denied this claim, saying that the aircraft never violated Belarusian airspace. Ukraine's border service also said helicopter and drone flights are needed to strengthen protection along the shared 1,084-kilometer (672-mile) border with Belarus.

What is happening on the border between Belarus and Ukraine?

Belarus argues Ukraine presents a security threat due to military drills taking place on the border involving 8,000 troops. Ukraine has been on edge over Moscow piling up troops near its borders. Kyiv fears Russia could make use of Belarusian territory to launch an attack.

The Washington Post reported US intelligence believes Russia has put in place 175,000 troops with an eye toward invading Ukraine. Russia has denied it has any plans to accelerate the pace of armed conflict in Ukraine.

ar/dj (AP, Reuters)