US officials believe that Russia has not yet taken retaliatory measures against Ukraine's drone attack last weekend and is likely to launch a new attack on many fronts.
Some US officials said the Russian response could take place in the next few days and will use a combination of aerial weapons, including missiles and UAVs.
The Russian Defense Ministry has said the missile and UAV attack on Kiev was a response to actions it called terrorism by Ukraine. However, US officials say a comprehensive response from Russia has yet to take place. A Western diplomatic source said the attacks would intensify, possibly targeting iconic targets such as the Ukrainian government headquarters, in order to send a strong message to Kiev.
A senior Western diplomat said that Russia could carry out a "destructive, fierce and persistent" attack. Meanwhile, expert Michael Kofman predicted that Russia will target intelligence facilities such as the headquarters of the Security Service of Ukraine (SBU) or defense production centers. He also noted the possibility of Russia using medium-range ballistic missiles, but said that Russia's ability to scale attacks is limited due to the use of much of its military power in recent times.
The Ukrainian UAV attack, part of a campaign nicknamed spider network, is believed to have destroyed about 10 of the total 20 Russian aircraft hit. Although Russia denied any losses, many Russian military bloggers confirmed that some of the aircraft were severely damaged, including those capable of carrying nuclear weapons.
Russian President Vladimir Putin told President Donald Trump in a phone call that Moscow would have to retaliate against the attack. Mr Trump then told the press it might not be beautiful and advised Mr Putin not to do that.
