Jordan and the Emirates have condemned the assassination of Iranian nuclear scientist Mohsen Fakhrizadeh, which Iran blames on Israel, although both Arab countries have normalised relations with Israel.
The UN, EU, Britain, Lebanon, Qatar, Oman and Syria have also condemned the killing. Lebanese Hizbullah and Palestinian Hamas joined the chorus as their leaders have also been targeted by Israel.
Iraq has expressed fear that pro-Iranian militia groups could take revenge against US forces in Iraq and draw it into a conflict between Iran and the US. Since he took office in 2009, Israeli prime minister Binyamin Netanyahu has been spoiling for a fight with Iran.
Hizbullah has said it is up to Iran to respond while Tehran has put pressure on Iraqi militia allies not to provoke the US. Iran does not want conflict to erupt before the withdrawal from Iraq of 500 of the remaining 3,000 US troops by mid-January and the Trump administration is out of office on January 20th.
Despite an outcry from the public and hardliners in parliament, Tehran has urged restraint due to the victory in the US election by Joe Biden, who seeks to re-engage with Iran.
President Hassan Rouhani has said Iran would retaliate at the "proper time". He is determined to give the US the chance to re-enter the 2015 agreement for lifting sanctions on Iran in exchange for severely limiting its nuclear programme. President Donald Trump withdrew from the deal in May 2018 and has imposed round after round of sanctions.
Tehran is under existential pressure to secure relief from sanctions, which have cut oil exports dramatically, shrunk the economy, devalued the currency and blocked medical supplies to battle Covid-19. It is predicted that 57 million of Iran’s 81 million people will live in poverty by the end of this year.
While many US experts on Iran agree that the assassination is illegal and damaging, there is division over its impact. Some believe Biden’s efforts to return to the nuclear deal will be undermined. Others argue the murder could encourage both sides to expedite US re-commitment to the deal.
This could mean that the US would not demand amendments to the original deal since changes could involve lengthy negotiations.
Once the US is back in the deal, Biden will be obliged to lift dozens of sanctions imposed by Trump on Iran and its allies. This process could take time since Biden will encounter fierce opposition from both houses of Congress, forcing him to resort to Trump’s practice of using presidential decrees to ease sanctions.
To reduce opposition, Biden has said that after the US has resumed compliance, he would take up the issue of Iran's ballistic missile programme and involvement in Syria, Lebanon, Iraq and Yemen.