The United States government has issued a travel advisory warning its citizens against visiting 23 countries classified as high-risk destinations due to security concerns.

The advisory, released by the U.S. Department of State’s Bureau of Consular Affairs on Wednesday, placed the countries under Level 4 — “Do Not Travel” — the highest travel warning category.

According to the department, Level 4 advisories are issued based on local conditions and the government’s ability to provide assistance to American citizens in affected countries.

“The U.S. government may have very limited ability to provide emergency services to U.S. citizens in Level 4 countries,” the advisory stated.

The listed countries are spread across Africa, Asia, Europe and the Middle East, with reasons including armed conflicts, terrorism risks, political instability, crime and limited access to consular support.

Among the countries on the list are Chad, the Democratic Republic of the Congo, Niger, Uganda, Haiti, Iran, Russia and Ukraine.

 Full list of countries under the U.S. Level 4 travel advisory

* Afghanistan
* Belarus
* Burkina Faso
* Burma (Myanmar)
* Central African Republic (CAR)
* Chad
* Democratic Republic of the Congo (DRC)
* Haiti
* Iran
* Iraq
* Lebanon
* Libya
* Mali
* Niger
* North Korea
* Russia
* Somalia
* South Sudan
* Sudan
* Syria
* Uganda
* Ukraine
* Yemen

The U.S. government advised citizens to avoid travelling to the listed countries “for any reason” and urged travellers to review official guidance before making international travel plans.