The heads of the British and American foreign intelligence agencies said on Saturday that Ukraine’s surprise incursion into Russia is a significant achievement that could change the narrative of the grinding two-and-a-half-year war.

Richard Moore, the head of MI6, said Kyiv’s surprise move in August to seize territory in Russia’s Kursk region was “typically audacious and bold on the part of the Ukrainians, to try and change the game”. He said the offensive had “brought the war home to ordinary Russians”.

Speaking alongside Moore at a rare public event in London, CIA director William Burns said the offensive was a “significant achievement” that had exposed vulnerabilities in the Russian military.

Burns also warned of the growing and “troubling” defence relationship between Russia, China, Iran and North Korea that he said threatens both Ukraine and Western allies in West Asia. North Korea has sent ammunition and missiles to Russia to use against Ukraine, while Iran supplies Moscow with attack drones.

Burns said the CIA had yet to see evidence of China sending weapons to Russia, “but we see lot of things short of that”. And he warned Iran against supplying ballistic missiles to Moscow, saying “it would be a dramatic escalation”.

The two spymasters also wrote an opinion piece for the Financial Times, calling for a ceasefire in Gaza and saying their agencies had “exploited our intelligence channels to push hard for restraint and de-escalation”. They said a ceasefire in Israel’s war against Hamas “could end the suffering and appalling loss of life of Palestinian civilians and bring home the hostages after 11 months of hellish confinement”.

Burns has been heavily involved in efforts to broker an end to the fighting, traveling to Egypt in August for high-level talks aimed at bringing about a hostage deal and at least a temporary halt to the conflict.

So far there has been no agreement, though US officials insist a deal is close. US President Joe Biden said recently that “just a couple more issues” remain unresolved. Israeli Prime Minister Benjamin Netanyahu, however, has said reports of a breakthrough are “exactly inaccurate”.

“I cannot tell you how close we are right now,” Burns told an audience at the FT Weekend Festival in London. He said that while 90 per cent of the text has been agreed between the warring sides, “the last 10 per cent is the last 10 per cent for a reason”.