The drone strikes on Russian air force bases weaken Moscow’s ability to wage war on its neighbor and undermine its capacity to threaten more distant rivals.

Though the knock-on effects are unclear, some military commentators have called the strike Russia's "Pearl Harbor." Hopes for direct peace talks, which resume Monday, remain low.

Russian and Ukrainian delegates are meeting in Istanbul on Monday for their second set of direct peace talks, a day after Kyiv launched a shock drone attack on Russia’s nuclear-capable bombers.

The second recent round of direct discussions, in Istanbul, resulted in an agreement to trade more prisoners, but produced few steps toward ending the fighting.

Ukraine and Russia met in Istanbul on Monday to exchange memorandums on a possible ceasefire to end Vladimir Putin’s three-year war, despite a gulf remaining between the two sides’ positions.

Russia and Ukraine have concluded their second round of peace talks, which came after the two countries traded overnight attacks. While the meeting was under way in Istanbul, Ukrainian President Volodymir Zelensky joined a summit with the leaders of Nato's eastern and Nordic members in the Lithuanian capital of Vilnius.

By making harsh, uncompromising demands in peace talks with Ukraine while continuing to pummel it with waves of missiles and drones, Russian President Vladimir Putin is sending a clear message: He will only accept a settlement on his terms and will keep fighting until they’re met.

Ukrainian President Volodymyr Zelenskyy on Sunday praised Ukraine's Security Service for "brilliant operation" aimed at "military targets" on Russian territory.