President Joe Biden on Friday warned Iran that the United States would "act forcefully" to protect Americans, after the US military carried out air strikes against Iran-backed forces in retaliation for an attack in Syria.
Later, officials said that another US service member was wounded on Friday in the latest tit-for-tat strike between Iran-backed forces and US personnel in Syria.
That comes on top of seven casualties on Thursday, which Washington blamed on a drone of Iranian origin, and included an American contractor being killed and five US troops and another contractor being wounded.
Suspected US rocket fire on Friday targeted new areas in eastern Syria, according to two local sources, with no casualties reported. Pro-Iranian forces in Syria said in an online statement late Friday that they have a "long arm" to respond to further US strikes on their positions.
Although US forces stationed in Syria have been attacked with drones before, deaths are rare.
"Make no mistake: the United States does not ... seek conflict with Iran, but be prepared for us to act forcefully to protect our people," Biden told reporters during a visit to Canada.
Asked whether there should be a higher cost for Iran, Biden replied: "We’re not going to stop."
The Pentagon had said US F-15 jets on Thursday attacked two facilities used by groups affiliated with Iran's Revolutionary Guards Corps (IRGC).
The Syrian Observatory for Human Rights said the US strikes had killed eight pro-Iranian fighters. Reuters was unable to independently confirm the toll.
Iran's state Press TV said no Iranians had been killed and quoted local sources as saying the target was not an Iran-aligned military post, but that a rural development center and a grain center near a military airport had been hit.
