The governors of New York, New Jersey and Connecticut announced on Wednesday that they would impose a 14-day quarantine on visitors from states with high coronavirus infection rates.

"We worked very hard to get the viral transmission down. We don’t want to see it go up," said Governor Andrew Cuomo during a joint press conference with his fellow tri-state governors.

The order in New York, which will take the form of a travel advisory, goes into effect at midnight. The standard for measuring states considered a risk will be those with more than 10 coronavirus cases per 100,000 people or whose infection rate is above 10 percent based on a seven-day rolling average.

As of Wednesday, Cuomo said there are nine states that fit that criteria: Alabama, Arkansas, Arizona, Florida, North Carolina, South Carolina, Washington, Utah and Texas. But more than two dozen states are seeing surges in cases.

The advisory not only applies to out-of-state residents. Any New Yorker that leaves to visit those states would be subject to quarantine upon their return, Cuomo said.

Governor Andrew Cuomo appears in a press conference with New Jersey Governor Phil Murphy and Connecticut Governor Ned Lamont.

The decision, which had been bandied about for several days, amounts to a vindication for Cuomo, whose state was once the epicenter of the pandemic and now has one of the lowest infection rates. In late March, Dr. Deborah Birx, a leading member of the White House coronavirus team, advised anyone who had been in the state to place themselves into 14-day quarantine.

Not long afterwards, President Donald Trump himself floated the idea of quarantining the tri-state region, but eventually backed down after sharp criticism from Cuomo that it would amount to an illegal lockdown.

"This would be a declaration of war on states. A federal declaration of war," Cuomo said at the time.

The infection rate in New York state is now 1.1 percent, while the number of total hospitalizations is now at 1,071, the lowest since March 19th.

Although it was not clear how the three states would enforce the quarantine, Cuomo denied that the measure was simply symbolic.

"You violate the quarantine, you will have to do mandatory quarantine and you will be fined," he said, adding that airlines had been informed of the travel advisory.

Violators may be asked to pay a minimum fine of $2,000 and up to $10,000 if they cause harm, according to the governor.

Early into the crisis, Cuomo had made efforts to present a unified front with neighboring states. But in practice, New Jersey and Connecticut have all reopened at their own pace.

Currently, eight states, including Florida, Rhode Island and Maine, currently have some form of travel restriction or quarantine requirement on visitors.

Murphy, whose state had the second most deaths from the virus, called Wednesday's travel advisory "a smart thing to do."

He said the residents of his state had "been through hell and back," adding, "The last thing we need to do is subject our folks to another round."