Brexit represents an opportunity for Britain to boost its global military standing and “enhance our lethality” in response to the threats posed by Russia and China, the defence secretary will say in a notably combative address at a defence thinktank.

Gavin Williamson intends to argue in a speech at the Royal United Services Institute on Monday that a post-Brexit UK should redefine its role as a global power prepared to intervene against countries that “flout international law”, backed up by new military technologies and capabilities.

The cabinet minister, who is increasingly keen to talk up Brexit at a time when a deal is elusive, is expected to say leaving the EU will allow the UK “to consider how we not only project but maximise our influence around the world in the months and years to come”.

Williamson is expected to conclude: “Brexit has brought us to a great moment in our history. A moment when we must strengthen our global presence, enhance our lethality and increase our mass.”

Allies of the minister indicated that Williamson would detail new technologies to spell out what he meant by boosting the lethality of the armed forces, stemming from a belief that future threats are more likely to come from well-resourced states rather than Islamist or other terrorist groups.

“Russia is resurgent rebuilding its military arsenal” and Nato must “develop its ability to handle the kind of provocations that Russia is throwing at us”, the minister will say nearly a year after the poisoning of Sergei and Yulia Skripal in Salisbury, which Moscow is widely suspected of orchestrating.

The defence secretary wants the UK to step up its presence in Asia with a new military base – a generation after Harold Wilson retreated from “east of Suez” – and will confirm that the first of Britain’s next-generation aircraft carriers, the Queen Elizabeth, will tour the Pacific as part of its maiden voyage in around 2021.

The flagship is likely to tour the South China Sea at a time of growing tensions regarding China’s territorial ambitions. Last September a British warship, the HMS Albion, sailed close to islands claimed by China in an attempt to demonstrate that the UK does not recognise claims beyond the internationally agreed 12-mile limit. China described the action as provocative.

Williamson is expected to argue that he wants people to see the UK as an international power capable of unilateral intervention despite the disaster of Iraq and refusal to engage significantly in Syria. “This is why ‘global Britain’ needs to be much more than a pithy phrase. It is about action,” he will say.

“And our armed forces represent the best of global Britain in action: action to oppose those who flout international law; and action, on occasion, that may lead to us intervene ourselves.”

The minister will confirm that cash – understood to be in the tens of millions – will be set aside for investment in offensive and defence cyberwarfare capability to contend with a threat associated with Russia and China, confirming reports from last September that the number of specialist hackers will increase from 500 to 2,000.

Labour’s Nia Griffith, the shadow defence secretary, said Williamson’s rhetoric was undermined by cuts to the defence budget of £9bn in real terms since 2010.

“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,” she said.

Last November, following a prolonged standoff with Downing Street and the Treasury, the Ministry of Defence was awarded an extra £1bn in the budget to fund Williamson’s technological ambitions, which came on top of £800m that had been handed to the department in the summer.

Williamson raised eyebrows when he asked mid-level army officers in December to submit to him 1,000-word essays on how to boost Britain’s global influence after Brexit.