Biden warns Iran of forceful action after US base attacked in Syria.

President Joe Biden has warned Iran that the United States will “act forcefully” to protect Americans, after the US military carried out air strikes against Iran-backed forces in retaliation for an attack in Syria. The violence could further aggravate already strained relations between Washington and Tehran, as attempts to revive a 2015 nuclear deal between Iran and major powers stalled. The US strikes were a response to a drone attack earlier on Thursday on a base near Hasakah in north-east Syria operated by a US-led coalition battling the remnants of Islamic State.