TUNIS, (Reuters) – Tunisian police have arrested nine men, including two officers, and charged them with plotting to kill U.S. servicemen taking part in joint military exercices in the North African country, a defence lawyer said on Monday.

Tunisia has been clamping down on radical Islamists over the past few years and has jailed more than 1,000 people, many of whom planned to join insurgents in Iraq to fight U.S.-led forces there and. Most are still in prison.

“A report by police investigating the case said the suspects planned to carry out an attack against the American officers during the joint exercices as part of military cooperation between Tunisia and the U.S.,” Samir ben Amor told Reuters.

Two of the suspects are army officers from a Tunisian military base in the coastal town of Bizerte, 60 km (37 miles) north of Tunis, he said. They were charged with attempting to steal weapons and explosives from the base and use them to attack the U.S. servicemen, ben Amor said.

The suspects will probably face trial next month, he said. He did not say when the attack was due to be carried out.

Tunisia is a staunch ally of the United States and the two countries have had close military ties since the early 1960s.

Tunis government officials were not immediately available for comment.