Ukraine has claimed to have struck a Russian industrial facility producing fuel for missiles, as Moscow says it has foiled several assassination plots on senior officers.Kyiv said on Thursday that its air force had had carried out a strike in Russia’s Rostov region on a factory which was used to produce solid fuel for ballistic missiles used in attacks on Ukraine.

Russia’s top security agency says it has arrested four Russians accused of making preparations to kill senior Defense Ministry officials on Ukraine's orders.

Russia’s Federal Security Service said on Thursday it had foiled several plots by Ukrainian intelligence services to kill high-ranking Russian officers and their families in Moscow using bombs disguised as power banks or document folders.

To ensure the safety of civil aircraft flights, temporary restrictions have been introduced on the operation of Sheremetyevo, Domodedovo, Vnukovo, Zhukovsky and Kaluga airports,” Russia’s aviation authority said.

"Ukraine was brutally attacked on Christmas Day," said Keith Kellogg, President-elect Donald Trump's pick for Ukraine and Russia envoy.

The missile has been branded as Ukraine's answer to dwindling Western aid, building self-reliance in defense technologies.

A massive Russian missile and drone barrage on Ukraine's energy infrastructure on Christmas morning was "inhumane," Ukrainian President Zelenskyy said.

Russia wants a legally binding deal for a lasting peace in war-torn Ukraine that would ensure the security in the region, Foreign Minister Sergei Lavrov said.

A Russian general who was wanted by Ukraine for using chemical munitions was killed by a remotely detonated bomb in Moscow on Tuesday, Russian authorities said.

Igor Kirillov, who was named the head of Russia’s nuclear defense forces in April 2017, was under sanctions from several countries including the U.K. and Canada for his role in Ukraine.

“While other countries of the world are celebrating Christmas, Ukrainians are continuing to suffer from endless Russian attacks,” Ukraine’s human rights ombudsman Dmytro Lubinets wrote on Telegram.