Three men, including a Syrian, have claimed responsibility for a rocket attack Oct. 22 against the Self-Defense Forces camp in southern Iraq, saying they wanted to force the troops out of the country, local sources said Saturday.

It is the first time the involvement of a non-Iraqi militant in an attack against the SDF troops has been reported, renewing concerns about the safety of the troops despite the government's repeated claim that the area is relatively stable.

The three were quoted by the sources as saying they belong to an Islamic group active in central and southern cities such as Basra, Nasiriyah and Najaf.

The group is allied with a militant group in Fallujah, the sources said.

By law, the government is allowed to deploy SDF troops in Iraq only in "noncombat" zones.

A dud rocket landed Oct. 22 in the SDF camp in Samawah, the first inside the wire since Japanese troops were deployed there in January. There were no injuries or damage to facilities as it had no fuse.

The three men did not disclose why the weapon had no fuse, the sources said.

Another rocket hit without exploding last Sunday, damaging a steel container.

The three men insisted they staged the attack to threaten the "occupation force of the SDF" to withdraw from Iraq.

It was not clear whether they were involved in last Sunday's attack.

The three people also admitted their involvement in the blast in early October at a Japan-Iraq friendship monument in Samawah, saying they had planned to destroy the monument and asked another group to carry it out, the sources said.

Nearly 600 Japanese ground troops are stationed in Samawah on a reconstruction mission.