Britain needs to focus on nuclear weapons, not soldiers, says the former director of nuclear policy.

Rear Admiral Philip Mathias, who held the post from 2005 to 2008, warned that the British military should look to a modernized Russian nuclear force as its primary concern, along with China's rapidly growing nuclear arsenal.

He made the comments in response to an article by General Lord Dannatt, former commander-in-chief of the British Army, which argued that in light of Russia's invasion of Ukraine, increased British defense spending should be focused primarily on improving the combat effectiveness of ground forces.

In an article for the Daily Telegraph, Mathias wrote that providing Britain with a credible nuclear deterrent against both of these totalitarian states should be a priority for any increase in defense spending, for it is this capability that they fear most and which will deter their expansionist ambitions.

Nuclear weapons are usually classified as strategic or tactical, with the former being used to win a war and the latter to win an individual battle.

According to the British security think tank Rusi, the range of Russia's tactical arsenal is limited to about 300 miles, compared with 3,000 miles for a strategic nuclear missile.

Meanwhile, Sir Stephen Lovegrove, Britain's former national security adviser, warned earlier this year that the West and China could miscalculate their way to nuclear war. He said Britain has clear concerns about Beijing expanding and modernizing its nuclear arsenal, adding that China's contempt for arms control agreements is a frightening prospect.