Iran�s Foreign Ministry spokesman has described as the latest wave of attacks against US bases in neighboring Iraq as �suspicious,� saying it appears that external elements, such as the Israeli regime, are behind such operations.

In an interview with Al Jazeera Arabic on Wednesday, Saeed Khatibzadeh was asked about the rocket attack earlier in the day that targeted the Ain al-Assad air base hosting American and other foreign forces in the western Iraqi province of Anbar.

In response, he drew attention to the similar nature of the attacks that have recently targeted US military bases and diplomatic missions in Iraq, saying the raids have all taken place in a specific manner and period of time.

Such attacks are thus �suspicious,� and there are indications that foreign hands, including those of the Zionist regime in Israel, are involved, the Iranian official said.

On Wednesday, a barrage of Grad rockets were fired at Ain al-Assad, the latest in a series of attacks on American military and diplomatic facilities in the Arab country. Two American contractors reportedly died in the raid.

No group has claimed responsibility for the attack on Ain al-Assad, but Washington usually pins the blame for such raids on so-called �Iran-backed� forces of the Popular Mobilization Units (PMU) � known in Arabic as Hashd al-Sha�abi, a claim that they have roundly rejected.

Commenting on the incident, White House Press Secretary Jen Psaki said at a briefing that the United States was assessing whether a further response is warranted.

�We are still assessing the impact of this latest rocket attack, including determining precise attribution,� Psaki added.

The raid on Ain al-Assad came around a week after the US military conducted an airstrike against positions of counter-terrorism PMU forces on the Iraqi-Syrian border, where they were in the middle of fighting the remnants of Daesh in coordination with the governments in Baghdad and Damascus.

Washington claimed the airstrike was a response to recent attacks on its military base in Erbil and its mission in Baghdad�s Green Zone, which it baselessly blamed on Iraq�s Kata�ib Hezbollah, a PMU faction.

In response to a question about Washington�s planned action, Psaki said the recent bombing by on areas east of Syria by US troops �was calculated proportionate and fully covered by legal authorities.�

�That will be our model, moving forward,� she added. �If we assess a further response is warranted, we will take action.�

Khatibzadeh, however, said America is not in a position to decide who had been behind such attacks, but it is up to Iraq, as a sovereign state, to make such a decision.

The US, he said, violated Iraq�s sovereignty by attacking the positions of a Hashd al-Sha�abi that is currently serving to protect the volatile border with crisis-hit Syria, adding that the PMU � an official Iraqi force � likewise condemned the US raid on its border positions as a violation of Iraq�s sovereignty.