Children born overseas to some American parents serving in the military or working for the federal government may no longer automatically claim U.S. citizenship if their parents had lived in the United States for less than five years, according to a new federal policy issued Wednesday.

Instead, officials said, those parents must apply for citizenship on behalf of their children before they turn 18 years old.

U.S. Citizenship and Immigration Services, which processes citizenship applications, said it rescinded a policy that had allowed some members of the military and government employees to easily transmit citizenship to children born overseas, because it conflicted with other policies and federal law.

The policy takes effect on Oct. 29 and applies only to children born afterward, officials said.

Acting USCIS director Ken Cuccinelli said the new policy does not affect people who were born and raised in the United States.

“This policy update does not affect who is born a U.S. citizen, period,” Cuccinelli said. “This only affects children who were born outside the United States and were not U.S. citizens. . . . This policy update does not deny citizenship to the children of U.S. government employees or members of the military born abroad.”

Pentagon spokeswoman Lt. Col. Carla Gleason said she “understands the estimated impact of this particular change is small.”

Still, changing the rules stirred widespread confusion Wednesday amid concerns about the Trump administration’s emphasis on restricting immigration and amid fears that federal employees and military workers — including those deployed to military bases or dangerous countries — might not have the ability to protect their own children.

The Trump administration has cracked down on immigrants in the military, all but shuttering a program that recruited immigrants with key language and medical abilities and expelling some recruits because of their family backgrounds. President Trump and past administrations have also faced criticism for deporting veterans, generally those who had been convicted of crimes, including minor offenses.

Some immigration lawyers said there is no guarantee that the government will approve citizenship applications.

Martin W. Lester, an immigration attorney in Chattanooga, Tenn., and chair of the American Immigration Lawyers Association’s military assistance program, said children born overseas to U.S. citizen parents usually can automatically claim citizenship as long as their parents had lived in the United States for five years, including for two years after they turned 14.

In the past, he said, federal immigration officials created exceptions for members of the military and government employees who did not meet that standard because they left the United States to serve the U.S. government overseas.

Now, he said, the new rule creates “second-class” citizenship for those parents who left before the five-year mark to serve the United States abroad.

“I don’t understand how changing this policy makes America safer by telling its servicemen and women and its government employees that it’s going to make it harder for their children to be Americans,” he said. “Who possibly thought that this was a good idea?”

Officials said the existing policy conflicts with State Department guidance and a 2008 law, leading to confusion when issuing citizenship decisions. To obtain citizenship, these parents must apply for citizenship on their child’s behalf, by filling out a form and meeting other requirements.

Margaret Wong, a Cleveland immigration lawyer with an international client base, said she thought few citizen parents would be affected by the policy. But she said those that could fall under it should try to have their children born in the United States.

“I would tell them get back here and give birth,” Wong said.

Abigail Hauslohner, Paul Sonne and Alex Horton contributed to this report.