An exchange of rockets between Iran and Afghanistan last month occurred after Iran attempted to build clandestine military installations on its neighbour's territory, a senior Afghan police official said.
While rocket attacks from Pakistani soil on to Afghanistan's eastern border have gained considerable publicity in recent weeks, the skirmish in the west has attracted less attention.
According to General Mohammed Naieem Chaghansori, a senior official at police headquarters in Nimroz province, the incident occurred after Afghan border police discovered Iranians attempting to establish a base on Afghan territory. Afghan media reported in mid-October that two missiles from Iran landed in Nimroz.
The Afghan security forces shot two rockets in the direction of the Iranians and they retaliated by firing eight rockets into the Kang district of Nimroz province, General Chaghansori said.
One Afghan teenager was injured by an Iranian rocket. "The Iranians were trying to build a military base secretly but immediately we got to know of this and we prevented them from building a base," General Chaghansori said. "We tried to solve the problem through negotiations but [the Iranians] insisted: 'It's Iranian soil and we will build here.' After we realised they would not listen to us we shot a few rockets into the air."
General Chaghansori added: "The Iranian police are standing by to try and attack again but the Afghan border police will stand against them and not let them take this type of action." Shukria Barakzai, the chairwoman of the Defence Affairs Commission in the Afghan parliament's lower house, confirmed the exchange, and admitted similar incidents had occurred from time to time over the past nine months.
Ms Barakzai said it is likely that Iran is feeling "vulnerable" as Afghanistan prepares to sign a long-term strategy partnership with the United States.
"Of course Iran is very unhappy," she said. "They don't like to see this happening under their nose. Iran wants to show its power in Afghanistan."
While in some ways Iran and the US share the same goal in preventing a resurgent Taliban in Afghanistan, Iranian Interior Minister, Mostafa Mohammad-Najjar, has stated firmly that a strategic partnership between the US and Afghanistan would pose a threat to his country's interests.
Iranians are particularly opposed to permanent US bases in Afghanistan after international combat troops leave in 2014. And fears linger, even though the American ambassador, Ryan Crocker, has said the US has "no interest in permanent bases in Afghanistan" or any interest in trying to exert control on the region from Afghanistan.
However, the US is currently helping to expand Shindand Air Base in western Herat province, which borders Iran, and transform it into the main Afghan airforce training base in the country.
The commander of the Nato Training Mission in Afghanistan, Lieutenant General William B Caldwell, has already said US mentors and trainers will remain at the base until at least 2016.