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.

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.

President Vladimir Putin said on Thursday there was no time left this year to sign a new Ukrainian gas transit deal, and laid the blame firmly on Ukraine for refusing to extend the agreement that brings gas to Slovakia,

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

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

Vladimir Putin declared on Thursday that Russia was closer to reaching its goals in Ukraine and that the front line was advancing every day.

Ukraine could consider continued transit of Russian gas on the condition that Moscow does not receive money for the fuel until after the war, President Volodymyr Zelenskiy said on Thursday.

“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.

Russia's ballistic missile attack on Ukraine’s capital, Kyiv, killed at least one person; a Ukrainian attack on Russian border town killed six, officials say.

Moscow again struck Ukraine’s energy infrastructure, part of an effort to wear down the country. “In the trenches, there are no holidays,” one man said.

Iranian President Masoud Pezeshkian is set to visit Moscow on Jan. 17 and sign a cooperation agreement with Russian President Vladimir Putin, Russian state news agency RIA cited Iran's ambassador to Russia as saying on Thursday.