A statement issued by the Pentagon said that the strike on al-Tanf base was "a deliberate and coordinated attack" using "both unmanned aircraft and indirect fire."
Several hours after the attack, the pro-Hizbullah Lebanese daily Al-Akhbar reported that the "Allies of Syria Operations Room", part of the Iran-led resistance axis, was responsible for it.
The report claimed further that the attack was part of a "general bid" by the resistance axis to shift the balance of deterrence vis-a-vis the U.S. in Syria. It added that, in discussions between them over the past weeks, the heads of the resistance axis in Syria, Iran and Lebanon decided that axis forces in Syria would be reinforced.
Analysts say, the direct attack against al-Tanf base on Syrian soil likely serves as a message for both Israel and the Americans that Iranians are ready for war, and perhaps also to exert pressure ahead of renewal of nuclear talks.
U.S. Central Command's public affairs did not immediately respond to request for comment.
The al-Tanf base was attacked probably in retaliation for Israeli strikes on a Syrian military compound in Deir Ez-Sur that left many Syrian soldiers as well as pro-Iran militia men dead.
The "allies of Syria," a new group, swore to avenge the victims and the destruction caused in the strikes.
In the past, airstrikes attributed to Israel were carried out mostly from Lebanon, the Mediterranean Sea, or from Israeli territory, but in some cases, both the planes and the air-to-ground missiles that were launched had to overcome very new and very dense anti-aircraft defenses in central and western Syria, and especially around Damascus.
Other, unclaimed airstrikes largely blamed by local forces on Israel have attacked Iran-associated positions across Syria, including one such attack that hit the heart of the country in Palmyra.
A statement later released by the "Operations Room of the Allies of Syria" and aired by a number of outlets such as the Al Manar outlet affiliated with Hezbollah movement said "a decision has been taken to respond to this attack in retaliation for the souls of the martyrs and the blood of the wounded," adding that, "the response will be harsh."
The attack on al-Tanf base also came days after Israeli snippers shot dead Midhat Saleh, a well-known figure in Syria, in Ein el-Tineh, a village along the Israeli border in the Golan Heights.
According to Israeli media Saleh had been assisting the Iranian military presence against Israel in Golan region. If the Syrian claims are confirmed, it would mark the first time that Israeli snipers are known to have killed someone identified as an Iranian-linked target across the border.
Israel captured the Golan Heights from Syria in the 1967 Mideast war and later annexed the area. Most of the world does not recognize the annexation, though the Trump administration declared the territory to be part of Israel. Israel accuses Iran of building military bases near Golan which it sees as an existential threat.