US president Joe Biden has slammed Donald Trump as “un-American” for his remarks on Russia’s war in Ukraine and Nato.

He said Mr Trump’s comments have raised the stakes of the nearly two-year-old war in Ukraine, calling them a “dangerous and shocking and un-American signal to the world” as well as “an invitation to Putin to invade some of our allies”.

The president accused Mr Trump, the likely Republican nominee against whom he’ll run for re-election this year, of having “bowed down to a Russian dictator,” something he said no other American president had ever done.

He also noted that his twice-impeached predecessor’s remarks indicated that Mr Trump, despite having spent four years in the White House as President of the United States, does not understand what Nato is or how the half-century-old alliance works.

Ukraine will need £7bn over 10 years for its tourism sector to recover, the United Nations’ cultural agency said on Tuesday, adding that the two-year war had so far cost the country over £15bn in tourism revenue.

Russia’s full-scale invasion of Ukraine on 24 February 2022 triggered the deadliest conflict in Europe since World War Two, with no sign of an end to the war in sight.

“The damage continues to increase and the needs for the sector’s recovery continue to grow,” Krista Pikkat, director of culture and emergencies at Unesco, told reporters, adding that the lost revenue to the capital Kyiv alone was £8bn.

In an assessment ahead of the war’s two year anniversary, the Unesco estimated the cost of damage to cultural property at about £2bn, up 40 per cent from 2023.

It said 340 buildings had been damaged, including museums, monuments, libraries and religious sites.

Vladimir Putin’s troops have advanced along the “entire front line” in Ukraine as Kyiv was forced to switch to defensive operations, the country’s military warned.

The Commander-in-Chief of the Armed Forces of Ukraine, Colonel-General Oleksandr Syrskyi, said the situation was “difficult” and had changed with the advance of Russian forces.

“At this time, the situation can be assessed as difficult. The enemy is now advancing along almost the entire front line, and we have moved from offensive operations to conducting a defensive operation,” Syrskyi told German TV channel ZDF

“The objective of our defense operation is to exhaust the enemy’s forces, inflict maximum losses on him, using our fortifications, our advantages in terms of technology, in terms of using unmanned aircraft, means of electronic warfare, and maintaining prepared defense lines,” he added.