The West must be ready to face the 'deadly quartet' of global adversaries, analysts warn

• Last week's NATO summit which highlighted the threat and "systemic challenges" posed by Russia, China, North Korea and Iran.
• Geopolitical and defense experts say the West has to prepare itself to confront such adversaries.
• Former NATO chief George Robertson warned Tuesday that the U.K.'s armed forces must have the capacity to challenge a "deadly quartet" of rivals.

LONDON — Hot on the heels of last week's NATO summit that highlighted the threat and "systemic challenges" posed by Russia, China, North Korea and Iran, geopolitical and defense experts say the West must now prepare itself to confront such adversaries.

Former NATO chief George Robertson on Tuesday warned that the U.K.'s armed forces must have the capacity to confront a "deadly quartet" of rivals, as he launched a strategic review into Britain's defensive capabilities.

"We're confronted by a deadly quartet of nations increasingly working together," he said, in comments reported by Sky News.

"We in this country and the NATO alliance … have got to be able to confront that particular quartet as well as the other problems that are pervading the world," he added.

Robertson did not explicitly name the members of the quartet, but the other three countries are thought to be Russia, Iran and North Korea — countries that NATO last week described as posing a threat and systemic challenges to "Euro-Atlantic security."

The use of the word "deadly" to allude to China matches a ramping-up of rhetoric against Russia's ally in last week's NATO summit, where Beijing's status as an adversary was acknowledged more publicly than ever.

In the summit declaration, China was described as a "decisive enabler" of Russia's war against Ukraine and as posing "systemic challenges to