Vientiane, Laos. US Secretary of State Antony Blinken told Southeast Asian leaders Friday that the US is concerned about China's “increasingly dangerous and unlawful” activities in the disputed South China Sea during an annual summit meeting, and pledged the US will continue to uphold freedom of navigation in the vital sea trade route.

His comments at a meeting with the 10-member Association of Southeast Asian Nations’ drew swift condemnation from Beijing, which blamed US and other military presences from beyond the region for instability in the waterway, which Beijing claims almost in its entirety.

China has overlapping claims with ASEAN members Vietnam, the Philippines, Malaysia and Brunei, as well as Taiwan. About a third of global trade transits through the sea, which is also rich in fishing stocks, gas and oil. A series of recent violent confrontations between China and the Philippines as well as Vietnam have fueled concerns that China’s increasingly aggressive actions in the sea could spiral into a full-scale conflict.

Beijing has refused to recognize a 2016 international arbitration ruling by a UN-affiliated court in the Hague that invalidated its expansive claims and has built up and militarized islands it controls.

“We are very concerned about China’s increasingly dangerous and unlawful activities in the South China Sea which have injured people, harm vessels from ASEAN nations and contradict commitments to peaceful resolutions of disputes,” said Blinken, who is filling in for President Joe Biden, in his opening speech at the US-ASEAN summit. “The United States will continue to support freedom of navigation, and freedom of overflight in the Indo-Pacific.”

The US has no claims in the South China Sea, but has deployed navy ships and fighter jets to patrol the waters in a challenge to China’s claims.

In Beijing, Chinese Foreign Ministry spokesperson Mao Ning said US and other military presences from outside the region were the main source of instability in the sea.

“The increasing military deployment and activities in the South China Sea by the US and a few other non-regional countries, stoking confrontation and creating tensions, are the greatest source of instability for peace and stability in the South China Sea,” Mao said.

Chinese and Philippine vessels have clashed repeatedly this year, and Vietnam said last week that Chinese forces assaulted its fishermen in the disputed sea. China has also sent patrol vessels to areas that Indonesia and Malaysia claim as exclusive economic zones.

The US has warned repeatedly that it’s obligated to defend the Philippines -- its oldest treaty ally in Asia -- if Filipino forces, ships or aircraft come under armed attack, including in the South China Sea.

Philippine President Ferdinand Marcos Jr. complained to summit leaders on Thursday that his country “continues to be subject to harassment and intimidation” by China’s actions, which he said violated international law. He has called for more urgency in ASEAN-China negotiations on a code of conduct to govern the South China Sea. Officials have agreed to try and complete the code by 2026, but talks have been hampered by sticky issues including disagreements over whether the pact should be binding.

In another firm message to China, Blinken said the US is also committed to help protect stability across the Taiwan Strait. The US has in recent years stepped up support for Taiwan, including new military financing last month that sparked protest from China, which claims the self-ruled island as its own territory.

Blinken also attended an 18-nation East Asia Summit, along with the Chinese premier, Russian Foreign Minister Sergei Lavrov, and leaders from Japan, South Korea, India, Australia and New Zealand.

ASEAN has treaded carefully on the sea dispute with China, which is the bloc's largest trading partner and its third largest investor. It hasn't marred trade relations, with the two sides focusing on expanding a free trade area covering a market of 2 billion people.