In separate interviews on Sunday, two of President Joe Biden’s top officials echoed his sentiments that a Russian invasion of Ukraine appears to be imminent.

“As we've described it, everything leading up to the actual invasion appears to be taking place,” Secretary of State Antony Blinken told CNN’s “State of the Union” on Sunday. 

“I don't believe it's a bluff,” Defense Secretary Lloyd Austin told ABC’s Martha Raddatz in a “This Week” interview in Lviv, Ukraine, where the U.S. temporarily relocated its embassy operations early last week amid the ongoing standoff with Russia. "He has a number of options available to him and he could attack in short order."

On Friday, President Biden gave his clearest attestation yet that Russian President Vladimir Putin was imminently prepared to invade Ukraine, saying he is “convinced [Putin has] made the decision” to invade and warning such an attack could occur in the coming days, citing U.S. intelligence.

The United States on Friday upped its estimate of Russia’s troop strength for a possible Ukraine invasion to as many as 190,000, up from about 100,000 on Jan. 30, according to Michael Carpenter, the permanent U.S. representative to the Organization for Security and Cooperation in Europe.

The new estimate includes pro-Russian separatists inside Ukraine, the Russian National Guard and Russian troops in Crimea, which were not counted in previous assessments. A U.S. military official told The Associated Press that an estimated 40% to 50% of the ground forces surrounding Ukraine had moved into attack positions closer to the border.

The president called on Moscow to choose diplomacy as Russia continued to surge troops at Ukraine’s border, fueling fears of an imminent invasion that could threaten Europe’s post-Cold War security order. 

“Russia has a choice: between war and all the suffering that will bring, or diplomacy that will make a future safer for everyone,” Biden said from the White House. “There are many issues that divide our nation and our world. But standing up to Russian aggression is not one of them.”

Moscow has repeatedly denied that it has plans to invade Ukraine, but Russia on Sunday extended joint military drills with ally Belarus near Ukraine’s northern border, Belarus’ defense minister announced.

Blinken on Sunday expressed concerns that the extension of the military excercises might be another sign Russia is planning to invade. 

"Now they're justifying the continuation of 'exercises' that they said would end now, the continuation indefinitely of those quote-unquote exercises on the situation in eastern Ukraine, a situation that they created by continuing to ramp up tensions," he added.

The U.S. and other Western nations have long alleged that Russia will attempt to create pretext to invade. On Saturday, Vice President Kamala Harris said that the U.S. and its allies will impose crushing sanctions if Russia further invades Ukraine.

"Let me be clear, I can say with absolute certainty: If Russia further invades Ukraine, the United States, together with our allies and partners, will impose significant, and unprecedented economic costs," Harris said at the Munich Security Conference on Saturday.

Blinken noted Sunday that the U.S. will not unveil those sanctions ahead of invasion because it would give Putin and Russia the opportunity "to try and plan against them."

"The purpose of the sanctions in the first instance is to try to deter Russia from going to war," Blinken said. "As soon as you trigger them, that deterrent is gone and until the last minute, as long as we can try to bring a deterrent effect to this, we're going to try to do that."

Blinken, the nation’s top diplomat, said that Biden is willing to talk to Putin “at any time, in any format” in order to prevent war.

“We believe President Putin has made the decision, but until the tanks are actually rolling, and the planes are flying, we will use every opportunity and every minute we have to see if diplomacy can still dissuade President Putin from carrying this forward,” he said.

However, Blinken told CNN, recent events, including the extension of the troops in Belarus and the increase in shelling along the contact line, showed Putin well underway in laying the pretexts and groundwork for invasion, in line with findings of U.S. intelligence and previous Russian territorial grabs: “He is following the script almost to the letter."

“Despite President Putin’s continued buildup of troops on the border, aggressive rhetoric and now false flag operations and flooding of disinformation globally, we still hope and wish that President Putin would make the decision to take the diplomatic path,” Kristina Kvien, the acting U.S. ambassador to Ukraine told ABC News on Sunday.

“We have offered ways that we can address some of his security concerns, we’ve given him papers laying those out, and it would really be an easy decision for him,” she added. “All he has to do is decide to take the diplomatic path.

Acting Ambassador Kvien went on to say it would be “disastrous” for Russia to further invade Ukraine, “not only because Ukraine will fight and Russia will face casualties too, but also because Russia will face devastating sanctions.”

Blinken is set to meet with Russian Foreign Minister Sergey Lavrov on Thursday, and other nations have also appealed to Putin in an attempt to broker a diplomatic solution. French President Emmanuel Macron held a nearly two-hour call with Putin on Sunday before speaking to Ukrainian President Volodymyr Zelenskyy. Vice President Harris also met with Zelenskyy on Saturday at the Munich Security Conference.

Zelenskyy pressed for a cease-fire on Twitter Sunday, and called on Putin Saturday to meet in an attempt to resolve the crisis.

Austin pledged Sunday on ABC that "we will make sure that we do everything possible to protect our troops."

The U.S. has deployed 5,000 troops to Poland and Romania. Another 8,500 are on standby, and some U.S. troops are expected to move toward Bulgaria. Britain is sending hundreds of soldiers to Poland, offering more warships and planes, and doubling its personnel in Estonia. Germany, the Netherlands and Norway are sending additional troops to Lithuania. Denmark and Spain are providing jets for air policing in the Baltic Sea region.

"I think our troops will be fine," he said, when ABC's Raddatz pressed him on whether there is any risk to U.S. troops. "We will be very diligent in terms of thinking through the range of possibilities."

The Associated Press contributed to this report.