Last week, a senior US military official warned that attacks by Iranian-backed factions on bases housing US forces in Iraq, were pushing all sides towards uncontrolled escalation.
Over the past few weeks, rocket strikes have targeted Iraqi bases where members of the US-led coalition forces are stationed, with no one claiming responsibility for the attacks.
"We need their help in terms of getting the security situation under control and stabilised, but we also still retain our right of self-defence and we will exercise it," Esper informed reporters.
Asked whom he believes was behind the recent rocket attacks, Esper disclosed: "My suspicion would be that Iran is behind these attacks, much like they are behind a lot of malign behaviour throughout the region, but it is hard to pin down," Reuters reported.
Earlier on Monday, Abdul Mahdi's office announced in a statement that Esper had urged the prime minister to take steps preventing the bombing of the US forces' bases.
According to the statement, Abdul-Mahdi warned Esper that: "Unilateral decisions will trigger negative reactions that will make it more difficult to control the situation and will threaten Iraq's security, sovereignty and independence."