LONDON -- Polish and allied planes briefly scrambled early on Monday in Polish airspace, as Russia targeted nearby Ukraine with aerial strikes, the Polish armed forces said.

The Ukrainian air force issued a series of alerts early on Monday, saying Russian drones were targeting areas throughout much of Ukraine.

The operation commander of the armed forces in Poland "launched all available forces and resources at his disposal, the on-duty fighter pairs were scrambled, and the ground-based air defense and radar reconnaissance systems reached the highest state of readiness," the military said in a statement in Polish translated by ABC News.

The launches were "preventative in nature," the military said.

About three hours after that initial message, at about 7 a.m. local time, the military said the threat of Russian strikes had been reduced, so the Polish and allied warplanes had been returned to their usual activity.

"We inform you that no violation of the airspace of the Republic of Poland has been observed," the military said.

This is a developing story. Please check back for updates.