The US military is said to spend roughly $41.6m (£31.7) annually on Viagra alone – roughly five times the amount it would reportedly spend on transition-related medical care for transgender service members.

In announcing his decision that transgender people will no longer be allowed to serve in the military, Donald Trump did not provide any data to back up his assertion that “tremendous medical costs” would disrupt the US’s armed forces.

“Our military must be focused on decisive and overwhelming victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail,” Mr Trump wrote on Twitter.

It is estimated that transition-related medical treatment for transgender service members would cost the military between $2.4m and $8.4m annually, according to a Defense Department-commissioned study published last year by the Rand Corp.

In comparison, total military spending on erectile dysfunction medicines amounts to $84m annually, an analysis by the Military Times says, about 10 times the estimated spending on transition-related medical care.

Currently, thousands of troops serving in the military are transgender, and some estimates place the number as high as 11,000 in the reserves and active duty military, Rand reported.

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During the White House press briefing, Press Secretary Sarah Huckabee Sanders said Mr Trump's decision – which she defended as purely tactical – was made after “extensive discussions” with his national security team.