(NEXSTAR) — Russian armed forces are now “as ready as they can be” to launch an all-out attack on Ukraine, a senior U.S. official defense official in Washington warned Wednesday. The official spoke on the condition of anonymity due to the sensitivity of the information.

The official added that 80% of the troops along the Ukrainian border and inside Belarus had moved to “forward positions” as of Wednesday.

The Russian forces have “advanced their readiness to a point where they are literally ready to go – now,” the official said.

Demonstrators hold placards and flags as they attend a protest outside the Russian Embassy, in London, Wednesday, Feb. 23, 2022. Ukraine urged its citizens to leave Russia as Europe braced for further confrontation Wednesday after Russia’s leader received authorization to use military force outside his country and the West responded with a raft of sanctions. (AP Photo/Alberto Pezzali)

The words mirrored those of Secretary of State Antony Blinken, who told NBC in an interview that “Russia has positioned its forces at the final point of readiness across Ukraine’s borders — to the north, to the east, to the south — everything seems to be in place for Russia to engage in a major aggression against Ukraine.”

Fears of an imminent offensive were further heightened late Wednesday when the Kremlin said rebel leaders in eastern Ukraine have asked Russia for military assistance to help fend off Ukrainian “aggression.”

FILE – A Ukrainian marine looks on at a fighting position on the line of separation from pro-Russian rebels, Donetsk region, Ukraine, Jan. 7, 2022. A new poll finds little support among Americans for a major U.S. role in the Russia-Ukraine conflict. President Joe Biden has acknowledged the growing likelihood of a new war in Eastern Europe will affect Americans even if U.S. troops don’t deploy to Ukraine. Just 26% of Americans say the U.S. should have a major role in the conflict between Russia and Ukraine, according to a new poll from The Associated Press-NORC Center for Public Affairs Research. (AP Photo/Andriy Dubchak, File)

With Russian lawmakers having authorized Putin to use military force outside the country and Ukraine surrounded on three sides by more than 150,000 troops, the rumble of tanks did not appear far off.

Ukraine, after weeks of trying to project calm, imposed a nationwide state of emergency.

A woman walks by a large print at a photographic memorial for those killed in the confrontation between Ukraine’s military and the pro-Russia separatist forces in Sievierodonetsk, Luhansk region, eastern Ukraine, Wednesday, Feb. 23, 2022. Ukraine urged its citizens to leave Russia, and Europe braced for further confrontation Wednesday after tensions escalated dramatically when Russia’s leader received authorization to use military force outside his country and the West responded with a raft of sanctions. (AP Photo/Vadim Ghirda)

Ukraine’s president is rejecting Moscow’s claim that his country poses a threat to Russia and warns that a looming Russian invasion could cause tens of thousands of deaths.

President Volodymyr Zelenskyy made the comments in a video address early Thursday.

Speaking emotionally in Russia, he said: “The people of Ukraine and the government of Ukraine want peace. But if we come under attack that threaten our freedom and lives of our people we will fight back.”

Zelenskyy says he tried to call Russian President Vladimir Putin late Wednesday but the Kremlin remained silent.

The Associated Press contributed to this report.