LONDON, Sept 8 - The heads of the British and American foreign intelligence agencies said Saturday that Ukraine’s surprise incursion into Russia is a significant achievement that could change the narrative of the grinding 2 1/2-year war, as they urged Kyiv’s allies not to be held back by Russian threats of escalation.

Richard Moore, the head of MI6, said Kyiv’s surprise August offensive 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 — which Ukraine said has captured about 1,300 square kilometers (500 square miles) of Russian territory — had “brought the war home to ordinary Russians.”

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

It has yet to be seen whether Ukraine can turn the gains into a long-term advantage. So far the offensive has not drawn Russian President Vladimir Putin’s focus away from eastern Ukraine, where his forces are closing in on the strategically situated city of Pokrovsk.

President Volodymyr Zelenskyy has repeatedly pressed allies to let Kyiv use Western-supplied missiles to strike deep inside Russia and hit sites from which Moscow launches aerial attacks. While some countries, including Britain, are thought to tacitly support the idea, others including Germany and the U.S. are reluctant.

U.S. President Joe Biden has allowed Ukraine to fire U.S.-provided missiles into Russia in self-defense, but the distance has been largely limited to cross-border targets deemed a direct threat, out of concerns about further escalating the conflict.

Burns said the West should be “mindful” of the escalation risk but not be “unnecessarily intimidated” by Russian saber-rattling, revealing that there was a moment in late 2022 when there was a “genuine risk of the use of tactical nuclear weapons” by Moscow.

He also warned of the growing and “troubling” defense relationship between Russia, China, Iran and North Korea that he said threatens both Ukraine and Western allies in the Middle East. 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” of the relationship.

He did not say whether such missiles had already been sent. But two people familiar with the matter said the United States has told allies that it believes Tehran has transferred short-range ballistic missiles to Russia. They spoke on condition of anonymity to discuss a matter that has not been publicly disclosed.

The State Department said Blinken would participate in the U.S.-U.K. strategic dialogue on Monday and Tuesday that will cover Ukraine, the Middle East, China and the Indo-Pacific.

U.S. officials have long accused Moscow of meddling in American elections, and this week the Biden administration seized Kremlin-run websites and charged employees of Russian broadcaster RT with covertly funding social media campaigns to pump out pro-Kremlin messages and sow discord around November’s presidential contest. (ap/ez)