China's military exercises aimed at Taiwan including missiles fired into Japan's exclusive economic zone represent a "significant escalation," U.S. Secretary of State Antony Blinken said Friday, urging Beijing to back down.

China launched the drills following a visit by U.S. House Speaker Nancy Pelosi to Taiwan that infuriated Beijing, which claims the self-governed island as its own territory.

Blinken told reporters on the sidelines of a meeting with the Association of Southeast Asian Nations in Cambodia, however, that Pelosi's visit was peaceful and did not represent a change in American policy toward Taiwan, accusing China of using it as a "pretext to increase provocative military activity in and around the Taiwan Strait."

He said the situation had led to a "vigorous communication" during East Asia Summit meetings in Phnom Penh in which both he and Chinese Foreign Minister Wang Yi took part along with the ASEAN nations, Russia and others.

"I reiterated the points that we made publicly as well as directly to Chinese counterparts in recent days, again, about the fact that they should not use the visit as a pretext for war, escalation, for provocative actions, that there is no possible justification for what they’ve done and urge them to cease these actions," he said.

Blinken did not sit down one-on-one with Wang but said he had spoken with the Chinese foreign minister already about the possibility of a Pelosi visit to Taiwan before it had taken place during meetings in Bali, and had made the U.S. position clear.

As the East Asia Summit opened, Wang patted Russian Foreign Minister Sergey Lavrov on the shoulder as he entered the room and gave the already-seated Lavrov a quick wave before taking his own seat. Lavrov waved back in response.

Blinken, who entered the room last, did not even glance at Lavrov as he took his own seat about a half-dozen chairs away, or at Wang who was seated farther down the same table as Lavrov.

Ahead of the Phnom Penh talks, the U.S. State Department indicated Blinken had no plans to meet one-on-one with either man during the course of the meetings.

The talks came a day after WNBA star Brittney Griner was convicted of drug possession and sentenced to nine years in prison by Russia in a politically charged case amid antagonisms over the Russian invasion of Ukraine.

Blinken said the conviction and sentence "compounds the injustice that has been done to her."

"It puts a spotlight on our very significant turn with Russia’s legal system and the Russian government’s use of wrongful detentions to advance its own agenda using individuals as political pawns," he said.

'China won't isolate Taiwan'

Meanwhile, Pelosi said in Tokyo that China will not isolate Taiwan by preventing U.S. officials from traveling there, wrapping up her Asia tour highlighted by a visit to Taipei that infuriated China.

The Chinese have tried to isolate Taiwan, Pelosi said, including most recently by preventing the self-governing island from joining the World Health Organization (WHO).

"They may try to keep Taiwan from visiting or participating in other places, but they will not isolate Taiwan by preventing us to travel there," she said, defending her trip that some say has escalated tension in the region.

"If we do not speak out for human rights in China because of commercial interests, we lose all moral authority to speak out about human rights any place in the world," Pelosi said.

"China has some contradictions - some progress in terms of lifting people up, some horrible things happening in terms of the Uyghurs. In fact, it's been labeled a genocide."Pelosi said "the two big countries" - the United States and China - must communicate in areas such as climate and other global issues. "It isn't about our visit determining what the U.S.-China relationship is."

"Our friendship with Taiwan is a strong one. It is bipartisan in the House and in the Senate, overwhelming support for peace and the status quo in Taiwan," she said.

Pelosi said that China had launched the "strikes probably using our visit as an excuse."

Taiwan slams 'evil neighbour'

Taiwan blasted its "evil neighbour next door" on Friday after China encircled the island with a series of huge military drills.

During Thursday's military exercises, which continued Friday, China fired ballistic missiles and deployed both fighter jets and warships around Taiwan.

The People's Liberation Army declared multiple no-go danger zones around Taiwan, straddling some of the busiest shipping lanes in the world and at some points coming within 20 kilometres (12 miles) of the island's shores.

Beijing said the exercises will continue until midday Sunday, and Taipei reported that Chinese fighter jets and ships crossed the "median line" that runs down the Taiwan Strait on Friday morning.

On Thursday, China had canceled a foreign ministers’ meeting with Japan to protest a statement from the Group of 7 nations that said there was no justification for Beijing's military exercises, which virtually encircle Taiwan.

"Japan, together with other member of the G-7 and the EU, made an irresponsible statement accusing China and confounding right and wrong," Chinese Foreign Ministry spokesperson Hua Chunying said in Beijing.

When Japan's Foreign Minister Hayashi Yoshimasa began to speak Friday at the East Asia Summit, both Lavrov and Wang walked out of the room, according to a diplomat in the room who spoke on condition of anonymity in order to discuss the private session.

In the wake of the Chinese missile launches into Japan's economic zone, Blinken said the U.S. stands in "strong solidarity" with Japan following the "dangerous actions China has taken."