Russia has sent more forces to its border with Ukraine and could launch an invasion at any time, including during the Beijing Winter Olympics, US Secretary of State Antony Blinken said on Friday. He said Washington was continuing to "draw down" its embassy in Ukraine and repeated a State Department call to American citizens in Ukraine to leave the country immediately.Simply put, we continue to see very troubling signs of Russian escalation, including new forces arriving at the Ukrainian border," Blinken told a news conference in Melbourne. "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." Russia, which has more than 100,000 troops near Ukraine"s borders, denies Western accusations it may be planning to invade its former Soviet neighbour. The Winter Olympics are being hosted by Beijing until Feb. 20. "If we allow those principles to be challenged with impunity, even if it"s half a world away, that will have an impact here as well. Others are watching. Others are looking at all of us to see how we respond," Blinken said. The US State Department urged Americans in Ukraine to leave immediately because of what it called increased threats of Russian military action and Blinken said Washington would continue to draw down its embassy after it had ordered the departure of family members of staff at its mission in January. "We will continue that process and we"ve also been very clear that any American citizens who remain in Ukraine should leave now," Blinken said. The United States and its allies have warned Russia of harsh sanctions if it goes ahead with an invasion of Ukraine. Moscow says the crisis is being driven by NATO and U.S. actions, and is demanding security guarantees from the West, including a promise by NATO never to admit Ukraine. — Agencies