Jeremy Fleming, director of U.K. intelligence agency GCHQ, pictured in November 2019. Fleming delivered a speech in Canberra, Australia on Thursday in which he addressed the war in Ukraine.Jeremy Fleming, director of U.K. intelligence agency GCHQ, pictured in November 2019. Fleming delivered a speech in Canberra, Australia on Thursday in which he addressed the war in Ukraine.

The head of Britain's intelligence agency said Thursday that Russian President Vladimir Putin has underestimated the situation in Ukraine, but his advisors are scared of telling him the truth.

It looks like Putin has made a mistake. Jeremy Fleming, director of U.K. intelligence agency GCHQ, said in a speech in Australia that it was clear that he had misjudged the resistance of the Ukrainian people.

Fleming said the Russian leader had underestimated the economic consequences of the sanctions regime as well as Russia's military capabilities.

He said that Russian soldiers were short of weapons and were refusing to carry out orders, sabotaging their own equipment and even accidentally shooting down their own aircraft.

Even though we believe Putin's advisors are afraid to tell him the truth, what is going on and the extent of these misjudgments must be clear to the regime.

When contacted by CNBC, a person from the Russian government was not available.

Fleming didn't give any information on how GCHQ or British intelligence officials knew how Putin's inner circle felt about relaying the details of the invasion to the Russian leader. The Russian president felt misled by Russian military leaders who kept important information from him, according to newly declassified U.S. intelligence.

Kate Bedingfield, the White House communications director, told reporters that the failure to tell Putin what was really happening resulted in persistent tension between Putin and his military leadership.

Fleming said Thursday that Putin was still trying to gain ground in Ukraine despite all of this.

The plan is failing. He said that his Plan B has been more barbarity against civilians and cities.

Russian officials said this week that they would scale back their military activity in and around the cities of Kyiv and Chernihiv, an announcement that has been met with skepticism in the West.

It looked like they had been forced to make a change. They launched attacks in both of those places.