WASHINGTON - The United States launched overnight air strikes against Iran-backed groups in Iraq and Syria, drawing condemnation from both governments Saturday, and promised more to come in retaliation for a deadly attack on US troops.
The United States blamed Sunday's drone attack on a US base in Jordan on forces backed by Iran, but did not strike inside Iranian territory, with both Washington and Tehran seemingly keen to avoid all-out war.
But with tensions in the region already running high in the face of the Israel-Hamas war in Gaza, both Damascus and Baghdad joined Tehran in accusing Washington of undermining the stability of the whole region.
National Security Council spokesman John Kirby said US warplanes struck "more than 85 targets at seven facilities utilised by Iran's Islamic Revolutionary Guard Corps and the militant groups that they sponsor", three of them in Iraq and four in Syria.
"These targets were carefully selected to avoid civilian casualties," he added.
But Iraqi government spokesman Bassem al-Awadi said civilians were among at least 16 people killed in the US strikes in western Iraq.
"The security of Iraq and the region will find itself on the brink of an abyss" because of the strikes, Awadi said.
The Syrian foreign ministry said the strikes served to "inflame the conflict in the Middle East in an extremely dangerous way".
Iranian foreign ministry spokesman Nasser Kanani said the overnight operation was "another strategic mistake by the US government, which will have no result other than intensifying tension and instability."
Hamas, whose unprecedented October 7 attack on Israel sparked the current spiral of violence in the region, accused Washington of pouring "oil on the fire".
The Syrian army said "a number of civilians and soldiers" were killed in the strikes in eastern Syria, but the Syrian Observatory for Human Rights war monitor reported no civilian deaths.
The Britain-based Observatory said the strikes killed 23 pro-Iran fighters and others were now evacuating their positions for fear of more US strikes.
- Flurry of attacks -
US President Joe Biden underlined that the overnight strikes were only a beginning. "Our response began today. It will continue at times and places of our choosing," he said in a statement.
His National Security Council spokesman said Washington "did inform the Iraqi government prior to the strikes," but his remark drew an angry denial from Baghdad.
The Iraqi government spokesman called it an "unfounded claim crafted to mislead international public opinion" and the foreign ministry said it would call in the US charge d'affaires in Baghdad to deliver a formal protest.
Relations between the two governments have soured in recent months after Washington carried out previous air strikes against Iran-backed groups in Iraq in response to a flurry of attacks on US-led troops since the Gaza war began last October.
The two governments opened talks on the future of the US-led troop presence late last month after repeated demands from Prime Minister Mohamed Shia al-Sudani for a timetable for their withdrawal.
The United States has some 900 troops in Syria and 2,500 in Iraq as part of an international coalition against the Islamic State group, a jihadist organisation that once controlled swathes of both countries.
Its troops in Iraq are deployed at the invitation of Baghdad, but those in Syria are deployed in areas outside the control of the Damascus government.
They operate out of bases in the Kurdish-held northeast or in a small pocket of territory along the borders with Iraq and Jordan.
The Syrian military demanded on Saturday that Washington withdraw its troops.
"The occupation of parts of Syrian territory by US forces cannot continue," it said.
- 'Significant escalation' -
Analysts said the US strikes were unlikely to stem the flurry of attacks on US targets around the Middle East sparked by US support for Israel in its war on Hamas.
The strikes represent a "significant escalation," according to Allison McManus, managing director for national security and international policy at the Center for American Progress.
US and coalition troops have been attacked more than 165 times in Iraq, Syria and Jordan since mid-October with weapons including drones, rockets and short-range ballistic missiles.
The soldiers killed Sunday were the first American military deaths from hostile fire in the upsurge of violence.
With Biden running for reelection this year, Republican Speaker of the House Mike Johnson criticised the overnight strikes as too little, too late.
"Unfortunately, the administration waited for a week and telegraphed to the world, including to Iran, the nature of our response," he said in a statement.