An international air traveler is cleared by a U.S. Customs and Border Protection Officer inside the U.S. Customs and Immigration area at Dulles International Airport.Paul J. Richards | AFP | Getty ImagesThe White House issued a presidential proclamation on Friday night requiring many future immigrant visa applicants to show they can afford health care, a move that could make it harder for poor migrants to enter the U.S.The action, which is set to take effect in 30 days, would require applicants, including people with ties to family members in the U.S., to show they have health insurance or prove their financial ability to pay for medical care before being issued a visa that could lead to a green card.The proclamation wouldn’t apply to noncitizen children of U.S. citizens. Refugees and immigrants who won asylum are also excluded from the new requirement. The Wall Street Journal first reported on the proclamation shortly before it was released.The move marks the latest effort by President Trump to restrict immigrants’ ability to enter the U.S.The administration is poised to implement a rule this month that would require many of the same applicants to demonstrate that they wouldn’t become reliant on public benefits including Medicaid should they be allowed to immigrate to the U.S.The new requirement would take a further step, requiring anyone looking to move to the U.S. to enroll in private insurance — including as a dependent on a family member’s health plan — or possess the financial means to cover significant medical costs.The proclamation also allows entry into the U.S. for migrants who have the “financial resources to pay for reasonably foreseeable medical costs, ” but it doesn’t define the threshold for meeting that standard.Subsidized plans purchased on the Affordable Care Act insurance exchanges wouldn’t count as an eligible form of insurance under the White House’s new definition.Low-income immigrants living in the country legally can’t use Medicaid for their first five years, but they can receive premium subsidies if their incomes are low enough. Under the new White House policy, purchasing health insurance using subsidies would disqualify people from living in the country legally.”It’s classic Catch-22 for low-income immigrants,” said Larry Levitt, executive vice president at the Kaiser Family Foundation. “They’re eligible for subsidized health coverage through the ACA, but applying for that subsidized coverage means they can’t legally be in the country.”The administration, in its 2017 tax overhaul, moved to relieve American citizens from an ACA mandate requiring them to have health coverage or pay a penalty.In its proclamation, the White House said it was taking the additional step to safeguard the health-care system for American citizens by preventing immigrants from enrolling in Medicaid or going to emergency rooms with no insurance, requiring hospitals or taxpayers to cover the cost.”President Trump has taken action to promote immigrant self-sufficiency, which has long been a fundamental aspect of our immigration system,” the proclamation said.The new requirement will apply to potentially hundreds of thousands of people moving to the U.S. each year on immigrant visas, which allow people to become permanent residents. In the 2018 fiscal year, the U.S. issued a total of roughly 534,000 visas, a 4.6% decline from the previous year’s total, according to State Department data.Some of those visas, like those granted to noncitizen children of U.S. citizens, won’t need to comply with the new requirement.The U.S. issues about 1.1 million green cards a year, but people issued immigrant visas often wait years in backlogs before they are granted permanent resident status.