U.S. Secretary of State Antony Blinken warned Friday that Russia could attack Ukraine at “any time” and warned Americans to leave Ukraine immediately.

Blinken issued the warning in Australia after meeting leaders of the Quad countries, the United States, Australia, Japan and India. Blinken cited “troubling signs” regarding Russia, including adding to the more than 100,000 troops it has amassed at the Ukrainian border.

“As we’ve said before, we’re in a window when an invasion could begin at any time. And to be clear, that includes during the Olympics,” Blinken said at a joint news conference in Canberra.

“We’re continuing to draw down our embassy, Blinken said. “We will continue that process. And we’ve also been very clear that any American citizens who remain in Ukraine should leave now.”

Russia maintains it has no plans to invade Ukraine but wants the West to keep Ukraine and other former Soviet countries out of NATO.

Blinken is visiting Australia as part of a Biden administration effort to show its long-term strategic focus remains on the Asia-Pacific region and that the Ukraine crisis will not distract it from its main priorities.

Blinken began Friday’s meetings with his Quad counterparts with Foreign Affairs Minister Marise Payne of Australia, who said the two would discuss China, North Korea and Ukraine.

After the meetings, the Quad ministers vowed in a joint statement to cooperate more closely to ensure the Indo-Pacific region was free of “coercion,” a veiled reference to China’s economic and military expansion. 

They also promised to strengthen cooperation on the coronavirus pandemic, cyberthreats and counterterrorism, while condemning North Korea’s “destabilizing ballistic missile launches” in violation of U.N. Security Council resolutions.

Payne, who hosted the Quad meeting, said Wednesday the gathering sends a message to China that security in the region remains a priority for the United States. 

Payne said the Quad ministers were “voting with their feet in terms of the priority that they accord to issues” important to the Indo-Pacific. 

Blinken’s visit to Australia is his first trip there since an enhanced trilateral security partnership known as AUKUS — Australia, the United Kingdom and the United States — was announced in September. The agreement includes a deal to build nuclear-propelled submarines for Australia as part of enhanced deterrence against China’s military expansion across the Indo-Pacific region.

“The Quad is not a military alliance, but it is not lost on China that you have four democracies, all with a strong maritime presence and advanced military capabilities, concerned by the increasingly aggressive approach China takes with its neighbors,” said Charles Edel, the Australia chair of the Washington-based Center for Strategic and International Studies.

Blinken’s visit to Australia comes amid a growing partnership between China and Russia that was on display during Sunday’s meeting in Beijing between Russian President Vladimir Putin and Chinese leader Xi Jinping at the beginning of the Winter Olympics. The meeting occurred amid Russia’s military buildup along neighboring Ukraine’s borders and China’s increasingly assertive efforts to reunite Taiwan with the mainland.

In Beijing, Chinese officials have expressed wariness over the Quad and AUKUS.  

China criticized the U.S. Friday for trying to “discredit, suppress and contain” the country’s development after Blinken said earlier this week there were concerns “that in recent years, China has been acting more aggressively at home and more aggressively in the regions.”

Chinese Foreign Ministry spokesperson Zhao Lijian rejected the remarks, telling reporters at a daily briefing the U.S. revealed an “ideological bias.”

Zhao described the alliance as “a tool to contain China and maintain U.S. hegemony.”

The top U.S. diplomat’s weeklong trip includes Fiji as well as Honolulu, Hawaii.

Blinken will meet Saturday with Fiji leaders who consider fishing and climate change priority issues.

“We agreed to boost maritime security support for Indo-Pacific partners to strengthen their maritime domain awareness and ability to develop their offshore resources, to ensure freedom of navigation and overflight and to combat challenges such as illegal fishing,” Australian Foreign Minister Payne said after the meeting.