Want smart analysis of the most important news in your inbox every weekday along with other global reads, interesting ideas and opinions to know? Sign up for the Today’s WorldView newsletter.

Travel with me back to a faraway moment in 2016. British Prime Minister Theresa May, then carrying a still-fresh mandate to take her country out of the European Union, sought to make a polemical point about those who don’t have the nation’s interests at heart. Like the anti-immigrant populists on her right flank — and the ascendant presidential candidate across the pond — May took aim at supposed cosmopolitan elites in her midst.

“If you believe you are a citizen of the world, you are a citizen of nowhere,” May said in a speech. “You don’t understand what citizenship means.” That contention has become a running theme in the West’s politics, underlying President Trump’s tirades against “globalism” and far-right European attacks on Brussels and the internationalist workings of the European Union.

Citizenship, viewed through this nationalist lens, was something to be honored and defended from the outside world.

Now, leaders like Trump and May are laying siege to it. This week, both the Trump administration and May’s government moved to strip citizenship from women who had traveled to Syria to join the Islamic State. By doing so, their critics argued, they were undermining the rule of law in their own countries and the very meaning of citizenship there.

In both cases, the legality of the action remains in doubt. The British decision to revoke the citizenship of Shamima Begum — a 19-year-old Londoner who traveled to Syria four years before as a schoolgirl and recently gave birth — reportedly hinged on the presumption that she had dual British-Bangladeshi citizenship.

But Begum, whose only meaningful connection to Bangladesh is her parents’ heritage, does not have a Bangladeshi passport, according to Bangladeshi authorities — meaning that the British government’s decision would render her stateless and stranded in legal purgatory in a war zone.

A similar fate may await Hoda Muthana, who married an Islamic State fighter after leaving her home in Alabama in 2014. The Trump administration contends that she is not a U.S. citizen — even though she was born in the United States and traveled to Syria on an American passport. Nevertheless, the Trump administration declared Wednesday that Muthana would not be allowed to travel back. The move hinted at another mooted White House plan: A nativist project to rein in “birthright” citizenship.

“A lawyer for Muthana maintains she was born in the United States in 1994 and automatically obtained citizenship as her father had ceased to work as a [Yemeni] diplomat weeks before — circumventing a constitutional provision that denies birthright citizenship to the children of foreign diplomats,” noted my colleague Rick Noack. The lawyer also insisted that Muthana regretted her decision to join the Islamic State and was willing to come home to face justice.

“I don’t know if there are many Americans right now who hate ISIS as much as Hoda does,” the lawyer, Hassan Shibly, told my colleagues, using an abbreviation for the Islamic State. “Ultimately, I think she’s trying to face our legal system, and Trump is trying to give her a pass by saying she’s not in our jurisdiction.”

The two cases reflect a far wider problem. Western governments have wrestled for years with the challenge of reabsorbing nationals who join Islamist militant groups in the Middle East. European officials are particularly wary of bringing home Islamic State recruits for whom there isn’t sufficient evidence to successfully prosecute in the courts. That raises the unwelcome prospect of hundreds of possibly radicalized individuals simply rejoining society.

While the act of stripping citizenship is not unprecedented — Britain alone has revoked the citizenship of some 150 people since 2010, and other European countries followed suit — critics say the cases in the news this week highlight a worrying hypocrisy.

“We never consider stripping citizenship from serial rapists or mass murderers,” wrote H.A. Hellyer for The Post’s Global Opinions. “Indeed, the wife of the man most responsible for the most bloodshed in Syria, Assad, is a British national — and she hasn’t had her citizenship removed.”

Others pointed to the case of Jack Letts, a white British convert to Islam with dual Canadian-British citizenship, who has not been deprived of his statehood. Speaking to BBC Radio 4, Farhad Ansari, a lawyer who has represented two other people whose British citizenship was revoked, said that although Begum’s “criminality is very relevant,” the British policy on Islamic State recruits is “inherently discriminatory and racist in how it is applied.”

“A schoolgirl with solely British heritage who traveled to Syria to join a group responsible for terrible atrocities would, under the government’s own legal justification, still be British today,” noted Patrick Galey in Politico. “Shamima Begum isn’t. Irrespective of how we view the young woman, that’s a dual-standard that should concern us all.”

For Trump, his grandstanding over Muthana is conspicuous not least because he only recently threatened Europe about its unwillingness to take back Islamic State foreign fighters. It was yet another sign of the president’s eagerness to be rid of the conflicts in Syria — and any responsibility in helping clean up the disastrous mess left behind.

“A failure to take responsibility for one’s own citizens is a disaster on multiple levels,” wrote Daniel Byman of the Brookings Institution. “First, it suggests that a country is unable to handle its own security — a remarkable admission for Trump to make given his supposed pride in U.S. strength. If America, with all its resources, cannot handle the risk posed by one young woman who has agreed to stand trial, then our security problems are indeed grave."

Second, Byman added, the West will create a new world of problems if it forces war-ravaged countries in the Middle East to cope with Islamist militants who, in most cases, were radicalized in their home countries. “If the United States and Europe do not take back their citizens, some will be killed (which is perhaps what their governments not-so-secretly desire) but others will hide or flee to areas where they are safer,” Byman wrote. “This is a threat to their new host countries and a potential long-term terrorism risk.”

“More often than not,” tweeted Michael Hanna, a senior fellow at the Century Foundation, “efforts to appear tough on terrorism betray a fundamental cowardice and lack of faith in our own institutions to deal with these issues and threats through legal means.” Trump and May may want to turn their back on these citizens of “nowhere” out of political expedience, but they are still somewhere and still, at least for now, citizens.

Want smart analysis of the most important news in your inbox every weekday along with other global reads, interesting ideas and opinions to know? Sign up for the Today’s WorldView newsletter.‘