In an apparent bid to cut Kobane off from Turkey, two suicide car bombings struck the north of the town facing the border, the Syrian Observatory for Human Rights said, without giving an immediate casualty toll.
And the jihadists of the Islamic Jihad (IS) group sent in reinforcements from Jarablous to the west of Kobane, as shelling of the centre of town resumed towards the end of a relatively calm day.
The Syrian Kurdish forces in Kobane hailed the airdrop, saying it would "help greatly" in the town's defence against a nearly five-week offensive by the IS.
US Secretary of State John Kerry said it would have been "morally very difficult to turn your back on a community fighting ISIL," using another acronym for IS.
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And a senior administration official said the airdrop was in recognition of the "impressive" resistance put up by the Kurds and the losses they were inflicting on IS.
The supplies were "intended to enable continued resistance against ISIL's attempts to overtake Kobane," said US Central Command.
The US-led coalition has carried out more than 135 air strikes against IS targets around Kobane, and an AFP correspondent just across the border in Turkey reported a fresh raid this afternoon.
The main Syrian Kurdish fighting force in Kobane, the People's Protection Units (YPG), swiftly welcomed the airdrop.
"The military assistance dropped by American planes at dawn on Kobane was good and we thank America for this support," said spokesman Redur Xelil.
Xelil declined to detail the weapons delivered but said there was "coordination" over the drop.
"Weapons have been sent according to their needs, and this is the first batch, and included heavy weapons," said Halgord Hekmat, spokesman for Iraqi Kurdish peshmerga forces, without providing further details.