HARTFORD — Voters in Hartford and Norwich this week handily approved police-related measures to make their communities feel more welcoming to immigrants, but questions remain about how and when the new policies might be put into place.

And the U.S. Attorney’s Office in Burlington suggested that they raise “serious public safety concerns.”

The measures — a policing policy change in Norwich and an ordinance in Hartford — would both prohibit local police from sharing information on a person’s citizenship status with federal immigration authorities and would bar police from detaining a person based on their suspected immigration status.

In Hartford the ordinance passed on a 1,842-1,177 vote, while in Norwich the policy change passed, 1,346-296.

But officials in Norwich and Hartford say the measures were “advisory” and that Selectboards in each town will have to vote to approve them.

Hartford Selectboard member Kim Souza said the board could have implemented the ordinance without the public’s input but “decided as a board to put (the issue) to voters to get a sense of what the will of the town was.”

She said she suspects the Selectboard will approve the ordinance but she can’t speak for other members of the board.

If both boards approve the measures, it’s still unclear whether police will have to undergo any additional training, according to both Souza and Norwich Town Manager Herb Durfee.

Another question that’s been raised is how the policy change and ordinance conflict with two federal laws that say local police must share immigration information with federal authorities. Some have worried that the Hartford ordinance in particular would force local police to violate the federal law, which could result in police being denied federal grant funding.

Asked for comment about the two Upper Valley measures, the U.S. Attorney’s Office said “when communities enforce the law selectively, they undermine the rule of law that we depend on as a society. Selective enforcement of the law raises serious public safety concerns.”

“Public safety is at risk when states and localities take steps to sever the lines of communication between state and federal law enforcement,” the statement, provided via email by Kraig LaPorte, a spokesman for the U.S. Attorney’s Office, also said.

Hartford Police Chief Phil Kasten said in an email on Thursday he is “optimistic all legal nuances will be addressed” before a Selectboard vote to approve the ordinance. Kasten has openly opposed the ordinance in the past and at a Selectboard meeting last year at least one board member expressed concern that the chief might leave town if the ordinance was passed. Kasten on Thursday said he is “busy with my work here and (has) no immediate plans otherwise.”

In Norwich, Durfee said there is no current legal appeal to the policy.

“Officers comply with all policies of the Town, subject to local, state, and federal laws (to) which they swore an oath,” he wrote in an email.

Norwich and Hartford are two of four towns in the Upper Valley voting on welcoming measures this election season.

In New Hampshire, Lebanon residents will vote on a welcoming ordinance next week, and Hanover officials will hold a meeting on March 23 to decide what version of their welcoming ordinance — if any — should go on the Town Meeting warrant in May.