The message seemed to be clear. The rockets and drones fired at US bases in Iraq and Syria over the past week meant that members of Iraq's militias and Yemen's Houthi rebels were not pleased with the US' apparently unconditional support for Israel.
Since terror attacks on Israel by the militant Islamist Hamas on October 7, the Israeli military has been bombing the densely populated Gaza Strip, as well as preventing most food, water, fuel and medical supplies from entering the area. A blockade enforced by Israel since 2007 has restricted imports to the region and prevented most people from leaving.
The Israeli government has said more than 1,400 Israelis died in the Hamas attacks. In Gaza, more than 5,000 have since been killed by retaliatory Israeli bombing, according to the Hamas-run health authorities. The exact numbers cannot be independently verified, but the Gaza death toll continues to climb as the Israeli bombing and blockade continues.
As a result, the mood among members of armed groups in Iraq and Yemen that consider themselves Hamas allies is tense.
"Fuller Israeli intervention in Gaza risks an escalation by Hamas' allies in the so-called Axis of Resistance, an Iran-led regional alliance that also includes Lebanon's Hezbollah, various Iraqi paramilitary factions and the Houthi movement in Yemen," analysts at the US-based think tank The Century Foundation wrote in a commentary on October 16.
Which groups are involved?
Hezbollah is a larger militia group and also a political party based in Lebanon. Hezbollah's armed wing is classified as a terrorist organization by some countries.
In Iraq, the militias in question were created after 2014 when locals volunteered to fight the extremist "Islamic State" group in that country. This is why they are broadly known as the Popular Mobilization Forces, or PMF. The militias' ideologies vary and some now have political wings sitting in the Iraqi parliament. Others are more militant. Many are supported financially and tactically by Iran.
The Houthi rebel movement has been fighting a civil war with Yemen's official government since 2014, in part as a reaction to rising Saudi influence. The Houthis are also supported by Iran.
Senior members from two of Iraq's largest militia groups have expressed their opposition to what is happening in Gaza.
"If America enters this battle directly, we will consider all Americans legitimate targets," said Hadi Al-Amiri, leader of the Badr Organization, in a press statement two days after the Hamas attack.
"The Americans are essential partners in killing the people of Gaza and therefore they must bear the consequences," Jaafar al Hussein, spokesman of the Kataib Hezbollah, announced on the messaging platform Telegram on October 18.
The leader of Yemen's Houthi group has made a similar statement.
Gaza hospital bombing causes outrage across Arab world
Before the current conflict flared up, there had been some pause in hostilities between the US and the Iraqi militias, who have often said they want the US out of Iraq and who have previously fired rockets at US bases.
Since the October 17 bombing of a Gaza hospital, such attacks have started again. Militias have claimed responsibility for around 11 drone or rocket attacks on US bases in Iraq and Syria. One US serviceperson died as the result of a heart attack suffered during one of the attacks, and others were slightly injured but were able to return to duty afterwards.
Also in Iraq, local media reported military movements on Mount Sinjar, a high point from where rockets were launched against Israel in 1991 by the country's former dictator, Saddam Hussein. Senior militia members have also been seen in Lebanon and Syria, countries closer to Israel geographically than Iraq and Yemen.
Over the weekend, an American navy destroyer, the USS Carney, managed to intercept three missiles and several drones in the Red Sea. They were launched by the Houthi group in Yemen, although the US military has said the target was unclear.
Experts believe the chances of Iran actually going to war itself remain slim. But Iran's proxies — such as Hamas, Hezbollah and the militias in Iraq and Yemen — may act without sparking an immediate international crisis.
Researchers at The Washington Institute for Near East Policy reported on October 20 that several of Iraq's militias have created a new umbrella organization called the "Islamic Resistance in Iraq."
"Given the unfolding Gaza crisis and the potential for regional broadening of the war, Iran-backed militias want to show unity by folding their actions into one brand, essentially 'reporting for duty,'" researchers said in the report.
How much of a threat are attacks on US bases?
As yet, it's unclear whether the increase in attacks on US bases in Iraq and Syria are more than saber-rattling.
US National Security Council Spokesperson John Kirby recently told reporters that the US knew Iran was behind the attacks by its proxies.
"We know that Iran is closely monitoring these events and, in some cases, actively facilitating these attacks and spurring on others who may want to exploit the conflict for their own good or for that of Iran," said Kirby.
Iran has denied it is behind the attacks, saying the militias act with autonomy.
For the time being, the drone attacks and the paramilitary leaders visibly taking part in meetings in Lebanon can be considered mostly posturing, said Hamzeh Hadad, a visiting fellow with the Middle East and North Africa program at the European Council on Foreign Relations.
"It is important to understand that Iraqis — and this goes across the spectrum of political leaders, religious leaders, civilians — are pro-Palestinian rights," he told DW. "This attitude is nothing new and was the same before, during and after Saddam [Hussein]. Iraqis share that same sentiment with many Iranians. But this is not because of Iran. Iraqis have their own agency in this [attitude]."
'Time for sound policy judgment and restraint'
The drone attacks and anti-American sentiment aren't new either, added Hadad.
"Right now, they're just sending a message," he said. "But yes, there could be more serious consequences if we start seeing casualties."
There's no evidence that the Iraqi militias or the Houthis were involved in any way with the Hamas attack on Israel, Century Foundation analysts wrote in their commentary.
But, they also added, "if Israel goes all-in in Gaza, as Israeli officials have promised to do, America's military presence is unlikely to prevent Iran-led 'Axis of Resistance' factions from attacking. The United States will then be on the hook to intervene in support of Israel. That will, in turn, trigger attacks on US targets across the Middle East."
In a worst-case scenario, Iraqi militias could attack US bases in Iraq and Syria while the Houthis target them in Saudi Arabia and the United Arab Emirates, the analysts said. The Houthis could also directly attack those two countries, often considered US allies.
"As the US supports Israel in pursuing Hamas, it needs to do so without abetting atrocities against Palestinian civilians," the analysts concluded, "and without unleashing a broader war that will be a disaster for the United States and the Middle East."
Edited by: Martin Kuebler and Carla Bleiker