Since mid-October, US military forces in Syria and Iraq have faced more than 76 attacks from Iranian-linked groups, a Pentagon spokesperson on 4 December.
The attacks come in the wake of Hamas' 7 October surprise attack across Gaza's border, which killed 1,200 Israelis and Israel's subsequent assault on the strip, which has killed at least 15,500 Palestinians.
US forces are under increasing pressure in the region as it backs Israel in its war on Gaza, including with the provision of arms and international political backing.
At least 56 US soldiers have been injured by attacks from Iranian-linked militias in Iraq and Syria.
Iran and regional ally Hezbollah have disavowed the attacks, with both parties saying that each actor in the "resistance axis," which is made up of Iranian allies across the region, acts independently.
Analysts have told °®Âþµº that it is possible that Iraqi militias in Syria, in particular, are working independently of Tehran's orders. The groups are linked with Iran but do not receive their daily marching orders from it.
In response to the attacks, US forces have struck back against Iranian-linked militias in Syria and Iraq, with five fighters killed in Kirkuk, Iraq, on 3 December by an unmanned US aircraft.
US warships have also responded to missiles launched by the Yemeni Houthis in the Red Sea, which targeted Israel-linked commercial vehicles on 3 December.
The US vessel shot down three drones in the "hours-long assault," the US military said.
"These attacks, while launched by the Houthis in Yemen, are fully enabled by Iran. The US will continue all appropriate responses in full coordination with its international partners and allies," Deputy Pentagon Press Secretary Sabrina Singh said on 4 December.
US military officials have said that the attacks are aimed at evicting US troops from Syria and Iraq and that militias were attempting to take advantage of the Israel-Hamas war for their own gains.
During the week-long truce between Israel and Hamas, no new attacks were launched at US forces in Iraq and Syria.