Republican presidential candidate Ben Carson canceled a trip to Israel, citing “security concerns.”

Carson had been scheduled to travel to Israel on Dec. 27 and meet with Israeli government officials, and then travel to Kenya, Zambia and Nigeria, returning to the United States on January 2, 2016, according to the Washington Post.

“The trip has been cancelled due to significant security concerns,” campaign spokesman Doug Watts said in a statement Thursday. He did not say what the concerns were.

“They were of such a nature that we found it prudent not to put anyone at any kind of risk,” Watts also said.

Carson traveled to Jordan last month and visited two Syrian refugee camps.

Carson, a retired pediatric neurosurgeon, has been criticized for a lack of foreign policy experience.

Donald Trump, the current GOP frontrunner, likewise recently canceled a planned trip to the Jewish state. Trump was also supposed to land in Israel December 27, causing a mild political crisis for Benjamin Netanyahu, who is already on rocky terms with Muslim constituents. Trump has been in the middle of a media firestorm after announcing a plan to ban all Muslims from entering the US, raising questions as to whether Netanyahu should be seen meeting with him.