Marie Harf said President Donald Trump's controversial travel ban affecting several Muslim-majority countries may be legal, but it's not good policy.

The Supreme Court on Tuesday upheld the travel ban, which critics called a discriminatory “Muslim ban” but the administration argued was needed for security reasons.

At issue was whether the travel ban discriminates on the basis of nationality and religion in the government's issuance of immigrant visas. 

The travel restriction affects people from Iran, Libya, North Korea, Somalia, Syria, Venezuela and Yemen. Chad was recently removed from the list after the administration said that country had beefed up its information-sharing.

"If it's about national security, why is Saudi Arabi not on it?" Harf asked on "America's Newsroom," pointing out that more Americans have been killed by terrorist attacks perpetrated by Saudis than other countries on the list.

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Harf, a Fox News contributor who served in the Obama State Department, said she wants to take a hard look -- from a policy perspective -- at why countries made the list or not to see if the travel ban accomplishes what Trump and his supporters say it's supposed to.

"I'm still skeptical of that," Harf said, arguing that the ban was something that Trump promised during the campaign and he felt the need to follow through.

"I think there are ways to handle the terrorist threat under existing immigration laws that you do not need this kind of ban for."

Watch the "America's Newsroom" segment above, and see Judge Andrew Napolitano's thoughts on the Supreme Court ruling.

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