The U.S. is setting up a facility in Kenya to quarantine U.S. citizens who have been exposed to Ebola, and will not be transporting those who develop symptoms to the United States, senior administration officials said on Thursday.

The World Health Organization declared the Bundibugyo strain ​of Ebola, for which there is no approved vaccine or treatment, an emergency of international concern this month and cases are rising sharply. More than 900 suspected cases and more than 200 suspected deaths have ​been reported so far.

The Kenya facility is for high-risk Americans who have been exposed to the virus but are still asymptomatic, the officials said. It will also be equipped to provide more advanced care and support for U.S. citizens who develop symptoms until they are evacuated, the officials told reporters.

Patients who need to be evacuated will be taken to third countries, not the United States, the official said, because it is faster, and to protect Americans at home. They denied the decision was politically motivated.

Secretary of State Marco ​Rubio had said on Wednesday that “we cannot and will not allow any cases of Ebola to enter the United States” and the U.S. last week imposed entry restrictions on travelers who have been in the Democratic Republic of Congo, Uganda, or South Sudan in the past 21 days, including lawful permanent residents, known as green card holders.

The facility, approved by the Kenyan government, will become operational on Friday with a 50-bed unit, the U.S. officials said, with plans to add two biocontainment units, each capable of holding two patients, and three isolation units, each capable of holding four patients.

(Reporting by Ahmed Aboulenein and Doina Chiacu; Editing by Doina Chiacu)