Chinese Defence Minister Wei Fenghe said on Sunday that it was up to the United States to improve the bilateral relationship, as ties were at a critical juncture.

Repeating several times at an Asian security meeting that China only sought peace and stability, and was not an aggressor, he called on the United States to "strengthen solidarity and oppose confrontation and division".

He said China firmly rejected "U.S. smearing, accusations and even threats" in Defense Secretary Lloyd Austin's speech at the Shangri-La Dialogue meeting on Saturday.

"We request the U.S. side to stop smearing and containing China. Stop interfering in China's internal affairs. The bilateral relationship cannot improve unless the U.S. side can do that," Wei, dressed in the uniform of a general in the People's Liberation Army, told delegates.

Austin said on Saturday there had been an "alarming" increase in the number of unsafe and unprofessional encounters between Chinese planes and vessels with those of other countries. He added that the United States would stand by its allies, including Taiwan.

Russia's invasion of Ukraine has taken centre stage at the meeting, and Wei made a point of saying China supported peace talks and opposed "providing weapons, applying maximum pressure". He said China had not provided any material support to Russia.

"What is the root cause of this crisis? Who is the mastermind behind this? Who loses the most? And who stands to gain the most? Who is promoting peace and who is adding fuel to the fire? I think we all know the answers to these questions," he said, without addressing them or stating China's position.

Meia Nouwens, a Senior Fellow at the International Institute for Strategic Studies, said Wei's speech was consistent with Beijing's official line on Russia-Ukraine issues.

"He did also underline that China is a partner of Russia and not an ally of Russia and that they do not have an alliance," she said. "They're underlining that at the end of the day, Chinese policy has always been to pursue China's own interests and not tie itself to those other countries."

In an address via video link on Saturday, Ukrainian President Volodymyr Zelenskiy warned delegates that the invasion of his nation threatened the rules-based order and put the entire world in danger of famine and food crises.

UNCHANGED ON TAIWAN

Russia calls its actions in Ukraine a "special operation" that it says is not designed to occupy territory but to destroy its southern neighbour's military capabilities and capture what it regards as dangerous nationalists.

Addressing the issue of Taiwan, Wei said China's position on the island, which Beijing views as a province, was unchanged. He said the Chinese government sought "peaceful reunification" with Taiwan but reserved "other options".

"China will definitely realize its reunification," Wei said. "Those who pursue Taiwan independence in an attempt to split China will definitely come to no good end."

In Taiwan, Premier Su Tseng-chang said on Sunday that the island does not want to close the door to China and is willing to engage in the spirit of goodwill, but on an equal basis and without political preconditions.

South Korean Defence Minister Lee Jong-sup said at the Singapore meeting that his country would enhance its defence capabilities and work closely with the United States and Japan to counter North Korea's nuclear and missile threat. The South would also help North Korea if it denuclearised, he said.

Fiji's Defence Minister Inia Seruiratu said that for all the focus on military matters at Shangri-La Dialogue, more pressing threats were being ignored.

"In our blue Pacific continent, machine guns, fighter jets, grey ships and green battalions are not our primary security concern," Seruiratu said. "The single greatest threat to our very existence is climate change. It threatens our very hopes and dreams of prosperity."