"I think it's extremely significant that yesterday, Sunday, within a week of the (UN) resolution being passed, some chemical weapons were being destroyed," Kerry said.
"I think it's a credit to the Assad regime, frankly. It's a good beginning and we welcome a good beginning."
Experts destroyed missile warheads, aerial bombs and chemical mixing equipment Sunday on the first day of the campaign to eliminate Syria's chemical weapons, the UN said, after an alleged attack on civilians by pro-Assad forces brought the threat of US-led intervention.
The operation, performed by Syrian personnel under the supervision of international disarmament experts, took place under the terms of a UN Security Council resolution that will see Damascus relinquish the banned arms.
Russia pushed the UN disarmament drive as an alternative to US-led strikes on Syria, whose civil war had expected to feature in bilateral talks between presidents Barack Obama and Vladimir Putin on the margins of a regional summit in Indonesia.
But Obama scrapped trips to the Asia-Pacific Economic Cooperation (APEC) summit in Bali and the subsequent East Asia summit in Brunei because of the federal budget crisis gripping the United States, sending Kerry in his stead.