US Secretary of State Mike Pompeo said Wednesday that the United States is closely monitoring the outbreak of the coronavirus but doesn't want to "overreact".

Speaking to reporters on his plane as he flew to Europe, Pompeo said that he didn't want "to get ahead of any decisions or talk about internal deliberations" but that US authorities are watching closely for developments that could merit changes in travel advisories, "including banning travel".

"[T]he American people should know that there are enormous efforts underway by the United States government to make sure that we do everything we can to protect the American people and to reduce the risk all around the globe," he added.

Still, he said, the United States doesn't "want to react in a way that actually has the potential to make things worse and not better''.

Pompeo noted that the US had issued its highest level of alert for Wuhan, warning Americans to entirely avoid the city where the outbreak started.

"We will evaluate it on a continuous basis, literally hour by hour, whether that's the appropriate level in Wuhan and whether we get it right in other places," Pompeo said. "That includes travel advisories, a wide range of things, including banning travel."

Also Wednesday, Tedros Adhanom Ghebreyesus, director general of the World Health Organization (WHO), announced that he would reconvene the International Health Regulations Emergency Committee on Thursday to advise him on whether the outbreak constitutes a public health emergency of international concern, or PHEIC. Last week the committee found that it was too soon to make such a declaration.

Republican US Senator Tom Cotton of Arkansas on Tuesday called on the Trump administration to ban all commercial flights between the US and China to stop the spread of the coronavirus.

Two US airlines, United and American, have announced suspension of flights to China.

So far, five cases of coronavirus have been confirmed in the US, in Southern California, Arizona, Seattle and Nevada. More than 100 people were being tested for the disease across 26 states on Tuesday.

Cotton also said US citizens living in China should have the option to return to America, but only under ``appropriate, elevated monitoring".

A plane chartered by the US government to evacuate 201 Americans from Wuhu landed at March Air Reserve Base about 60 miles east of Los Angeles Wednesday morning. It was carrying diplomats from the US Consulate in Wuhan and other US citizens. Some of the passengers living in Wuhan paid their way to get out.

The flight departed Anchorage early Wednesday after refueling and after screenings were completed on the passengers.

All passengers had already been through two screenings in China and were monitored during the flight, said Alaska Health Department spokesman Clinton Bennett.

Anne Zink, Alaska's chief medical officer, said the passengers were excited to be back on American soil.

"The whole plane erupted in cheers when the crew said, 'Welcome home to the United States,'" she said.

The passengers will be quarantined for a period of time in California and won't be allowed to return to their homes immediately.

Tuesday night, the US Centers for Disease Control and Prevention (CDC) said in a statement that the passengers will be "monitored for symptoms post-arrival".

United Airlines said it was suspending some flights to mainland China beginning Feb 1 and lasting through Feb 8 because of a "significant decline in demand." United operates about a dozen flights a day to Hong Kong and mainland China.

American Airlines, the largest US carrier, said it will from Feb 9 through March 27 suspend flights from Los Angeles to Beijing and Shanghai, citing sagging demand in the wake of the coronavirus outbreak.

Reuters contributed to this story.