Russian President Vladimir Putin has vowed that Moscow will not relent in its invasion of Ukraine and plans to create a buffer zone to help protect against long-range Ukrainian strikes and cross-border raids.

The Kremlin’s forces have made battlefield progress as Kyiv’s troops struggle with a severe shortage of artillery shells and exhausted frontline units after more than two years of war.

The front line stretches over 1,000km (620 miles) across eastern and southern Ukraine.

Advances have been slow and costly, and Ukraine has increasingly used its long-range firepower to hit oil refineries and depots deep inside Russia. Also, groups claiming to be Ukraine-based Russian opponents of the Kremlin have launched cross-border incursions.

“We will be forced at some point, when we consider it necessary, to create a certain ‘sanitary zone’ on the territories controlled by the (Ukrainian government),” Mr Putin said late on Sunday.

This “security zone,” Mr Putin said, “would be quite difficult to penetrate using the foreign-made strike assets at the enemy’s disposal.”

He spoke after the release of election returns that showed him securing a fifth six-year term in a landslide election devoid of any real opposition following his relentless crackdown on dissent.

Monday marks the 10th anniversary of Russia’s seizure of Ukraine’s Crimea Peninsula, which set the stage for Russia to invade its neighbour in February 2022.

However, Mr Putin has been vague about his goals in Ukraine since that full-scale invasion floundered.

Mr Putin again warned the West against deploying troops to Ukraine. A possible conflict between Russia and Nato would put the world “a step away” from a third world war, he said.

French President Emmanuel Macron recently said that sending Western troops into Ukraine should not be ruled out, though he said the current situation does not require it.

Commenting on the prospects for peace talks with Kyiv, Mr Putin reaffirmed that Russia remains open to negotiations but will not be lured into a truce that will allow Ukraine to re-arm.

However, Ukrainian President Volodymyr Zelensky has apparently shut the door on such talks, saying Mr Putin should be brought to trial at the International Criminal Court in The Hague, which last year issued an arrest warrant for Mr Putin on war crime charges.

With crucial US aid being held up in Washington, US Senator Lindsey Graham arrived in Kyiv on Monday, the US Embassy said.

Ukraine desperately needs the around 48 billion dollars (£37.7 billion) that the package of support would provide, especially artillery shells and air defence systems.

Ukraine’s air force said it intercepted 17 out of 22 Shahed drones launched by Russia over various regions of the country overnight. Russia also fired five S-300/S-400 missiles at the Kharkiv region and two Kh-59 at the Sumy region, both in northeastern Ukraine, it said.

Authorities say the intensity of ground attacks and airstrikes has increased recently in the Sumy region, prompting the evacuation of 56 people, including 26 children, from one border village over the past week.

In the past two and a half months the region has been struck more than 3,000 times, after some 8,000 strikes over all of last year, the Ukrainian regional government says. The number of aerial bomb attacks has tripled, and Russian saboteurs are highly active, according to officials.