While the Russian Ministry of Defense said some of its troops positioned near Ukraine's border would begin returning to their bases, Secretary of State Antony Blinken told ABC's "Good Morning America" on Wednesday that the U.S. has seen "no meaningful pullback" and described the situation as "deeply, deeply concerning."

"On the contrary, we continue to see forces, especially forces in the vanguard of any renewed aggression against Ukraine, continuing to be at the border, to mass at the border," Blinken said, emphasizing the choice to deescalate is squarely on Russian President Vladimir Putin.

"President Putin's put in place the capacity to act on very short notice," he said. "He can pull the trigger -- he could pull it today. He could pull it tomorrow. He could pull it next week. The forces are there if he wants to renew aggression against Ukraine."

Amid some tensions between U.S. and Ukrainian officials over the level of urgency here, Blinken defended Ukrainian President Volodymyr Zelenskyy, saying the former comedian is "taking it very seriously. He's trying to maintain calm. He doesn't want his people to panic. That's the right thing to do. But I think the Ukrainians are taking it very, very seriously."

ABC News Anchor George Stephanopoulos asked Blinken directly if the threat of attack in Ukraine is "today greater than it was yesterday."

"From day to day, George, you can't say it's higher or lower. It's there. It's there. It's real. We haven't seen a pullback. We'd like to see one. If we see one, we would welcome it," Blinken said. "We're prepared for diplomacy. We're prepared for aggression prepared either way."

Kremlin spokesman Dmitry Peskov said Wednesday that Russia has "grown tired" of listening to "threats," referring to U.S. President Joe Biden's speech the previous night.

"We'd prefer not to listen to various sorts of threats as to what would happen to us if we did something that we have no intention of doing," Peskov told reporters during a daily call.

If the United States did not issue warnings about a Russian invasion of Ukraine and threaten consequences, then perhaps the Russian people would like Americans more, Peskov said.

"We have pretty much grown tired of [the threats]," he added. "If we heard such messages that would be free of threats, the Russian people would probably like them much more."

Peskov noted that Russia hopes it would be able to begin a "negotiating process" with the U.S. over the Kremlin's demands for security guarantees that Ukraine will not join NATO, as well as confidence building measures such as limits on missile deployments and troops exercises.

Biden during his speech Tuesday night again ruled out any guarantee on Ukraine’s potential NATO membership, saying the U.S. will not sacrifice fundamental principles and that countries have a right to choose their alliances. The Biden administration, however, has offered to engage with Russia on the confidence-building measures, which Western nations have put forward in the hope of persuading the Kremlin to choose a diplomatic route out of the crisis.

-ABC News' Patrick Reevell

Kremlin spokesman Dmitry Peskov said Wednesday that while he expects the "hysteria" in Western media outlets about the threat of a Russian invasion to continue, he hopes foreign journalists will ultimately admit that they were wrong.

During a daily call with reporters, Peskov was asked whether Western media reports that Russia would attack Ukraine on Wednesday could be described as the culmination of "information hysteria."

"Frankly, the way the Western hysteria is developing indicates there is still a long way until culmination. There won't be a remission any time soon, we should be patient," Peskov said. "Still, it is very important that Western media outlets, in this case, the British ones, say at least at the end of every day that their predictions have been wrong."

-ABC News' Anastasia Bagaeva

The Russian Ministry of Defense said Wednesday that troops from its Western Military District massed near Ukraine have completed loading their tanks and are now returning to their bases, some 1,000 kilometers (over 620 miles) away.

"Personnel of the units of the Western Military District's tank army have finished loading their tanks and tracked armored hardware onto flatbed railcars and have embarked on a 1,000-kilometer march using various means of transportation back to their permanent bases upon completion of their routine drills," the defense ministry said in a statement.

Russia has currently deployed forces from all of its military districts near Ukraine. The Russian military has said that the Western and Southern Military Districts are returning to their bases. Meanwhile, units from Russia's Eastern Military District remain in Belarus, having traveled some 10,000 kilometers (over 6,200 miles) there.

-ABC News' Patrick Reevell