Sir Ben told the BBC Radio 4 Today programme that the wrangling over Ukraine’s use of long-range missiles in Russia would benefit Putin.
“I’m just disappointed that it’s yet again, another tug of war around another capability,” he said.
The row over whether Western missiles can be used to strike targets across Ukraine’s border follows similar delays over decisions on supplying tanks and fighter jets.
“All of that delay, all of that tug of war favours Russia and allows Putin to insert, in the delay, threats and new red lines and efforts to divide and rule in the international community,” he said.
Sir Ben added that Putin was “a bully, and for a bully to succeed all he needs to do is intimidate people, all he needs to do is get people to pause and… that’s how he gets us to change our behaviour”.