The US presidential hopeful claims fewer Muslims serve in UK armed forces than in terror group – he’s wrong and here’s why

Donald Trump has claimed more British Muslims join Islamic State than join the British armed forces, but can that really be true?

The US Republican presidential candidate tweeted the statement in response to a petition demanding he be banned from the UK for his support of a “total and complete shutdown” of US borders to Muslims.

Donald J. Trump (@realDonaldTrump) In Britain, more Muslims join ISIS than join the British army. https://t.co/LQVNz7b2Eb

Trump’s tweets have been disputed in the past: he claimed in the same hour that the Sun’s Katie Hopkins was a respected columnist. But is this statistic true?

Where does this claim come from?

Trump is not the first to make this allegation and it is not a fringe opinion. The National Review article he links to has no figures but has a hyperlink to a Times article from August 2014, citing the Labour MP for Birmingham Perry Barr, Khalid Mahmood, who said there were “easily” 1,500 jihadis and about 560 Muslims in the armed forces. Those figures are in some dispute.

Facebook Twitter Pinterest Donald Trump’s comments on British Muslims prompted a show of solidarity outside an east London mosque. Photograph: Stefan Rousseau/PA

How many Muslims are in Britain’s armed forces?

According to a freedom of information request to the Ministry of Defence from 2014, there are 640 Muslims in the armed forces: 550 in the army, 40 in the navy and 50 in the air force.

Facebook Twitter Pinterest FOI from 2014. Photograph: FOI

How many Muslims are fighting with Isis?

Shiraz Maher, a senior research fellow at the International Centre for the Study of Radicalisation at King’s College London, estimates that 750 Muslims have gone to Syria to fight over the last three to four years.

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But that figure needs breaking down before we can definitively say there are more Muslims fighting in Isis than in the British army. Maher, who has dedicated his research to tracking British fighters, says many recruits in the beginning did not join Isis.

Isis is a fairly late actor. Most of those who went out in the earlier phases of the civil war were not joining Isis, they were going to Jabhat al-Nusra, and many other groups. Since last year, though, it has been pretty much one-way traffic to Islamic State, but at the beginning it was much more diverse and we don’t really know for sure where they went.

There are not 750 British people currently fighting with Isis – this is a cumulative figure. The British government estimates at least 260 have returned to the UK, which may be for a number of reasons, but many may have returned after becoming disillusioned at how different rebel groups were subsumed by Isis in the past two years.

Maher has counted 50 Britons who have died in combat, although the government’s estimate is 60. Many more fighters in that 750 figure who left for Syria are also likely to be dead or disengaged, but their whereabouts are unknown.

That leaves an estimate of approximately 430 to 440 British fighters alive and currently in Syria, and there is a good chance that the majority are with Isis, Maher said.

It is not really accurate to compare a cumulative number of fighters heading to Isis over a number of years with the current number of Muslim recruits in the British army. But we can say one thing:

At no point over the past three years has the number of active British Isis fighters eclipsed the number of serving Muslims in the British armed forces.