Al-Shabab extremists have overrun a key military base used by U.S. counterterror forces in Kenya, destroying U.S. aircraft and vehicles.

The U.S. military says the situation remains "fluid" after the pre-dawn attack by the al-Qaida-linked group.

Kenya's military says five attackers were killed. It is not clear whether U.S. or Kenyan forces were killed.

The Somalia-based al-Shabab released photos of blazing aircraft. It says the attack has nothing to do with the Middle East crisis.

This is the first known al-Shabab attack against U.S. forces inside Kenya, a key base for fighting one of the world's most resilient extremist organizations.

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