WASHINGTON — The Trump administration spent months hashing out new travel restrictions on more than a half-dozen countries, determined to avoid the chaos that accompanied President Trump’s first travel ban. But critics say it’s a mystery why some countries are included and they believe Venezuela and North Korea were added to provide legal and political cover for what they say remains a “Muslim ban.”

The new restrictions covering citizens of Chad, Iran, Libya, North Korea, Somalia, Syria, and Yemen – and some Venezuelan government officials and their families – are to go into effect Oct. 18.

As for the previous version, which expired on Sunday, the Supreme Court on Monday announced it would cancel arguments scheduled for next month to give both sides time to consider the implications of the new one. They have until Oct. 5 to weigh in.

Trump’s efforts to restrict entry into the U.S. have been the subject of lawsuits almost since the moment he announced the first travel ban in January, and the latest version is sure to attract new legal challenges – though experts are divided on how they might fare.

Avideh Moussavian, senior policy attorney at the National Immigration Law Center, said she saw little difference between the earlier bans and the new policy, despite the addition of two non-Muslim countries.

“What remains the same is the discriminatory core of these bans which were always designed to exclude Muslims from the United States,” Moussavian said.

But Stephen Yale-Loehr, an immigration expert at Cornell University, said the latest version is narrower and better explained, including about how the government decided which countries to target.

“The third time may be the charm for President Trump’s immigration travel ban,” Yale-Loehr said.

Administration officials have stressed the latest version is the result of a lengthy process, and based on an objective assessment of each country’s security situation and willingness to share information with the U.S.

The restrictions are based on new baseline factors such as whether countries issue electronic passports with biometric information to prevent fraud and report information about potential terror threats. That baseline was shared with countries across the globe, and they were given 50 days to comply.

Those that failed to satisfy the “objective process of measuring whether countries met the baseline” are now subject to new restrictions.

Critics said the inclusion of some countries appeared to be largely symbolic and intended to combat perceptions that the ban is targeting Muslims.

The new visa sanctions on Venezuela, for instance, apply only to officials from five government security agencies and their immediate families. Still, Venezuelan President Nicolas Maduro labeled the move a form of “political and psychological terrorism.”

The restrictions on North Korea will have little impact because so few of its citizens visit the United States.