Defence Secretary Ben Wallace has told a Tory conference fringe event that the lack of apparent military unity in the West gave Russian President Vladimir Putin an opportunity to invade Ukraine.
Speaking at the Conservative Party conference, the Defence Secretary told members that increasing the defence budget to 3% of GDP would boost the UK's military capabilities.
He believes that "3% of GDP, 2.5% of GDP by 2026 is the direction to travel, and we will be able to deliver for that something very important".
Mr Wallace also highlighted that the war in Ukraine exposed "all these Western armed forces that thought they could get away on 2% of GDP or less".
He questioned their attitudes toward defence spending and said "it looked good on the surface but underneath we didn't have the readiness, we didn't have the ammunition stocks, we didn't have the boring things that are so key to keeping the armed forces going".
The Defence Secretary does however maintain that big differences can still be made, should Western nations increase their military aid capacities for Ukraine.
Focus on "managed decline" in defence
Mr Wallace has also said he wants to stop the armed forces from being "hollowed out" as he revealed why he did not run to be the next prime minister.
The Defence Secretary backed Liz Truss in the Conservative party leadership contest over the summer and continued in his role in her Government after serving under Boris Johnson.
He also said he does not "have much of a life outside defence" because of his focus on addressing the "significant" problems of "managed decline" in defence.
The Defence Secretary said the Army is the "most conservative" organisation in the state as he set out his desire to reform it and invest in its future.
He said: "I don't really have much of a life outside defence because if I want to reform that department, a big old oil tanker that doesn't like change. I can tell you as an ex-soldier myself, the most conservative organisation in the whole of Government is probably the Army."
Watch: How might the military use extra funding?
Armed forces to be "properly ammo'd up"
The Secretary of State, now three years into his role, said: "I would like passionately when I leave politics to know we have started reversing the managed decline in defence we have seen for 40 years."
He emphasised the need for the armed forces to be "properly ammo'd up", adding: "Unless you spend the money on infrastructure, you won't be able to run your submarines and your ships and you tanks and you will end up with the Army I served in.
"You pressed the button in 1991, about 30% of our armoured vehicles never left the barracks."