A "fresher conversation" is needed to ensure the UK stays above NATO's defence spending target, the head of Armed Forces has said.
Admiral Sir Tony Radakin confirmed Defence Secretary Ben Wallace had issued a warning to Chancellor Rishi Sunak that the UK could miss the alliance's 2% spending commitment.
Countries in NATO are set a target aim of spending 2% of their gross domestic product (GDP) on defence – Mr Sunak allegedly ignored the Ministry of Defence (MOD) warning that the UK could fail to meet the alliance's spending commitments by 2025.
Mr Wallace was said to have warned Mr Sunak that Britain would not meet the 2% spending commitment because of rising inflation and the move to arm Ukraine's battle against Russia.
"We're a big-spending department and we have regular conversations at all levels with the Treasury," Admiral Radakin told TalkTV's The News Desk.
"The Defence Secretary writing to the Chancellor to say this is our view of where defence spending is going, I think is pretty normal business."
He went on: "At the moment, under this spending review, we're above 2% through the whole period. And then it starts to peter off, I think, in 2024/25.
"At the moment, the trajectory is going up and then it gets really close staying above 2%. Then that needs to be a fresher conversation, because the ambition of this Government is to stay above 2%."
Watch: Russia continues intensive focus on east Ukraine.
During the TalkTV interview, the Chief of the Defence Staff says the Russians were in for a "hard slog" and questioned whether the "rushed manner" in which President Vladimir Putin was seeking to achieve victory would succeed.
"I think what we're now seeing is incredible pressure – political pressure and military pressure – for a victory," he said.
"This is going to be a tough fight. And it's going to carry on being a tough fight. This is going to be a hard slog.
"You're seeing the tactical fight, where he's trying to rush to a tactical victory, and then he'll push that with his own people."
Admiral Radakin added: "We're talking severe impact on their armed forces. We've had 25% of their forces effectively being taken out – either through people being killed or through the damage to their battalion tactical groups."