|A still image, taken from video footage and released by Russia's Defence Ministry on August 18, 2016, shows a Russian Sukhoi Su-34 fighter-bomber based at Iran's Hamadan air base dropping off bombs in the Syrian province of Deir ez-Zor. Ministry of Defence of the Russian Federation
Iran's Foreign Ministry said Russia had stopped using the base for strikes in Syria, bringing an abrupt halt to an unprecedented deployment that was criticized both by the White House and by some Iranian lawmakers.
"Russian military aircraft that took part in the operation of conducting air strikes from Iran's Hamadan air base on terrorist targets in Syria have successfully completed all tasks," a Russian Defence Ministry spokesman, Major-General Igor Konashenkov, said in a statement.
"Further use of the Hamadan air base in the Islamic Republic of Iran by the Russian Aerospace Forces will be carried out on the basis of mutual agreements to fight terrorism and depending on the prevailing circumstances in Syria," Konashenkov said.
Last week, long-range Russian Tupolev-22M3 bombers and Sukhoi-34 fighter bombers used Nojeh air base, near the city of Hamadan, in north-west Iran to launch air strikes against armed groups in Syria.
It was the first time a foreign power had used an Iranian base since World War Two. Russia and Iran are both providing crucial military support to President Bashar al-Assad against rebels and jihadi fighters in Syria's five-year-old conflict.
Some Iranian lawmakers called the move a breach of Iran's constitution which forbids "the establishment of any kind of foreign military base in Iran, even for peaceful purposes".
Iranian Defence Minister Hossein Dehghan dismissed that criticism but also chided Moscow for publicizing the move, describing it as showing off and a "betrayal of trust."
"We have not given any military base to the Russians and they are not here to stay," Dehghan was quoted as saying by the Fars news agency late on August 21.
He said there was "no written agreement" between the two countries and the "operational cooperation" was temporary and limited to refueling.
The U.S. State Department, which last week called the move "unfortunate but not surprising" and said it was studying if it violated a U.N. Security Council resolution that bars supply, sale and transfer of combat aircraft to Iran, said that it was unclear if Moscow's use of the base had "definitively stopped."