Russia will respond to Ukraine's latest attacks as and when its military sees fit, the Kremlin said on Thursday, accusing Kyiv of state terrorism as U.S. President Donald Trump downplayed prospects for an immediate peace between the countries.

Russian President Vladimir Putin told President Donald Trump in a phone call Wednesday that he was obligated to respond to Ukraine’s weekend drone attack, Trump said, setting up a potential escalation in the conflict just as the US president hopes to broker an end to the war.

Moscow said on Wednesday that military options were "on the table" for its response to Ukrainian attacks deep inside Russia and accused the West of being involved in them. Russia also urged the United States and Britain to restrain Kyiv after the attacks,

With 41 military aircraft impacted, the Ukrainian drone attack was described by some commentators as Russia's "Pearl Harbor." The attack on Pearl Harbor in December 1941 was a surprise air raid by Japan on the U.S. during World War II. Kyiv's assault follows ground advances by Moscow troops in recent days in Ukraine's Sumy border region.

The Ukrainian Security Service says it detonated around 2,500 pounds of explosives under abridge linking Russia to Crimea, causing significant damage.

The Kremlin said Tuesday that negotiations on ending the war in Ukraine were "extremely complex" and that it would be wrong to expect any sudden breakthroughs, adding that it was waiting for Kyiv's reaction to its proposals.

The attack, which took place more than 4,300 km inside Russian territory, destroyed over 40 aircraft and marked the first known Ukrainian strike on strategic bombers stationed that far from the front lines.