KYIV, Ukraine (AP) -- Poland's defense chief traveled to Kyiv on Thursday in search of Ukrainian help in developing his country's drone warfare capabilities, just over a week after Russian drones entered Polish airspace and exposed NATO's vulnerability to drone warfare.

Drones used for defense and attack have taken a central battlefield role in the more than three years since Russia invaded Ukraine, transforming how wars are waged, and countries are keen to master the new and quickly developing battlefield technology.

"We will be signing an agreement concerning cooperation between the (defense) ministries, but also acquiring capabilities when it comes to operating drones," Polish Defense Minister W?adys?aw Kosiniak-Kamysz said in comments published on the website of the Polish Ministry of Defense.

Last week's Russian incursion, which caused NATO to send fighter jets to shoot down the drones, heightened tensions in eastern Europe. The war between Russia and Ukraine has continued despite months of U.S. efforts to stop it, including a U.S.-Russia summit meeting in Alaska.

The incursion deepened concerns that the war could spread beyond Ukraine.

NATO announced it was strengthening its defensive posture on its eastern flank bordering Belarus, Russia and Ukraine.

Moscow, meanwhile, showcased its conventional and nuclear military power in long-planned exercises with Belarus that fueled Western concerns about Russia's intentions.

Ukraine's air defenses shot down or jammed 48 out of 75 Russian drones launched at the country overnight, the air force said Thursday.

Rail infrastructure was again hit, part of a recent pattern of strikes.

Ukrainian President Volodymyr Zelenskyy said Wednesday that strikes on energy and railway infrastructure are meant to disrupt supply lines and create social tension.

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