The US military has increased the alert level at several of its bases in Europe, according to multiple American media outlets. The alert level has been raised to "Charlie," the second-highest level, as reported by ABC News and CNN, citing anonymous officials.

This alert level is activated "when an incident occurs or intelligence is received indicating a probable threat of terrorist activity or targeting against personnel or facilities," as outlined by the US military on its website. The highest alert level, "Delta," is implemented when a terrorist attack is ongoing or imminent.

While the US European Command did not confirm the change in status, it stated, "We remain vigilant." The Pentagon explained that "due to a range of factors that could impact the safety and security of US service members and their families stationed in the European theater, the US European Command is doubling down on the need for vigilance during the summer months."

The US State Department currently advises American citizens in Germany, where the US European Command headquarters is located, to exercise increased caution due to the threat of terrorist activities.

European countries are on high alert following an attack in the suburbs of Moscow in March, claimed by ISIS, which resulted in the deaths of about 150 people. France has also heightened its alert status in preparation for the Paris Olympics, and Germany is currently hosting the UEFA Euro 2024 football championship.