US officials said Soleimani was killed because forces under his command planned attacks on US targets
The West Qurna-1 oilfield is jointly developed by CNPC and Exxon Mobil, with the US major as the operator
Security has been beefed up around the White House amid heightened tensions with Iran
He reiterated that the nuclear deal signed in 2015 with six world powers could not be renegotiated