Britain cast China as representing an "epoch-defining challenge" to the world order, in an update to its foreign policy framework published on Monday which declared that the UK's security hinged on the outcome of the Ukraine war.

In the refresh of Britain's blueprint for security and international policy, the government warned of China's deepening partnership with Russia, and Moscow's growing cooperation with Iran following the invasion of Ukraine.

Only first released two years ago, Prime Minister Rishi Sunak said Britain's Integrated Review (IR) had been updated to take account of events, with the hardening of language and positioning towards Beijing and Moscow.

But the decision to still not describe China as a threat was likely to disappoint many in Sunak's governing Conservative Party, who also believe his vow to spend an extra 5 billion pounds ($6 billion) on defence is insufficient to support Ukraine without leaving Britain vulnerable.

"What could not be fully foreseen in 2021 was the pace of the geopolitical change and the extent of its impact on the UK and our people," Sunak wrote in a foreword to the IR.

"Since then, Russia's illegal invasion of Ukraine, weaponisation of energy and food supplies and irresponsible nuclear rhetoric, combined with China's more aggressive stance in the South China Sea and the Taiwan Strait, are threatening to create a world defined by danger, disorder and division."

Foreign Secretary James Cleverly told parliament on Monday China's size and significance connected it "to almost every global issue".

"We cannot be blind to the increasingly aggressive military and economic behaviour of the Chinese Communist Party, including stoking tensions across the Taiwan Strait," he said.

The unveiling of the update has been choreographed to coincide with Sunak's visit to San Diego to agree the next steps in a landmark defence agreement, AUKUS, with U.S. President Joe Biden and Australian Prime Minister Anthony Albanese

Of Britain's extra defence spending, 3 billion pounds will go towards nuclear projects, including help for Australia to build nuclear-powered submarines for the first time, part of efforts to counter China in the Indo-Pacific.

When it was first published in 2021, the Integrated Review described China as a "systemic competitor" - a term some in Sunak's party said was mealy-mouthed.

"China under the Chinese Communist Party (CCP) poses an epoch-defining and systemic challenge with implications for almost every area of government policy and the everyday lives of British people," the updated document said.

"It has pursued rapid and opaque military modernisation with huge new investments, militarised disputed islands in the South China Sea, and refused to renounce the use of force to achieve its objectives with regard to Taiwan."

While it outlined that Britain would step up its national security protections and boost work with partners in the region, the government said its preference remained for better cooperation and understanding with Beijing.

"But we believe that this will depend on the choices China makes, and will be made harder if trends towards greater authoritarianism and assertiveness overseas continue," it said.

Russia Threat

While saying tensions in the Indo-Pacific "could have global consequences greater than the conflict in Ukraine", Britain said Russia still remained the most acute threat.

"What has changed is that our collective security now is intrinsically linked to the outcome of the conflict in Ukraine," the IR added.

Britain and other Western countries have scaled up their pledges of military aid for Ukraine this year, with promises of tanks and armoured vehicles, as well as longer-range weapons.

On the other hand, they have expressed concern at support for Russia being potentially offered by China and Iran.

"China's deepening partnership with Russia and Russia's growing cooperation with Iran in the wake of the invasion of Ukraine are two developments of particular concern," the IR said.

With Sunak under pressure to do more to help the defence ministry combat inflation and replace weapons sent to Ukraine, two billion pounds will go towards replenishing and increasing conventional stockpiles and investing in munitions infrastructure.

He also outlined an "aspiration" to increase defence spending to 2.5% of gross domestic product in the longer term.