The UK needs a bolder and stronger armed forces prepared to use “hard power” or risk being seen as a “paper tiger”, the defence secretary will say.
Gavin Williamson will warn in a speech that Britain must stand up to those who “flout international law”.
He will also say that the UK has its “greatest opportunity” to redefine its position on the world stage after Brexit.
Labour said the military had been “completely undermined” by Tory cuts.
Speaking at the Royal United Services Institute on Monday, Mr Williamson will unveil plans to modernise the armed forces, and say it must increase its “mass and lethality”.
He will also confirm the Royal Navy’s new aircraft carrier HMS Queen Elizabeth is being deployed to the Pacific region, where China has been involved in a dispute over territorial claims in the South China Sea.
The carrier will take part in the mission along with F-35 jets from the UK and US.
Mr Williamson is to use his speech to outline how cyber forces will be reinforced thanks to a “very significant investment”, which will be used both to defend and launch attacks.
The defence secretary won an extra £1.8bn for defence in the last budget.
With the boundaries between peace and war becoming “blurred” – particularly by Russia and China, he will claim – Mr Williamson will say Britain and its allies had to be ready “to use hard power to support our interests”.
He will go on to say: “We have to be ready to show the high price of aggressive behaviour. Ready to strengthen our resilience.”
Defending interventionist policy, he will say the cost of failing to act in global crises had often been “unacceptably high”, and that Western powers cannot “walk on by when others are in need”.
“To talk but fail to act risks our nation being seen as little more than a paper tiger,” he will add.
Shadow defence secretary Nia Griffith said: “The UK’s ability to play our role on the international stage has been completely undermined by eight years of Tory defence cuts.
“The Conservatives have slashed the defence budget by over £9bn in real terms since 2010 and they are cutting armed forces numbers year after year.
“Instead of simply engaging in yet more sabre-rattling, Gavin Williamson should get to grips with the crisis in defence funding that is happening on his watch.”
Gavin Williamson: Armed Forces have to be prepared to use hard power}