(CNN) Russia could double the number of troops it has on Ukraine's border in "relatively short order," Secretary of State Antony Blinken warned Wednesday after meeting with Ukrainian leaders.
Blinken's meetings with Ukrainian President Volodymyr Zelensky and Foreign Minister Dmytro Kuleba in Kyiv Wednesday were the first of three stops the top US diplomat is making this week amid warnings from the US that Russia, which has amassed tens of thousands of troops near near Ukrainian borders, could launch an invasion at any point.
"As we meet today, Russia has ratcheted up its threats and amassed nearly 100,000 forces on Ukraine's border, which it could double on relatively short order," Blinken said during a press conference alongside Kuleba.
Blinken will meet with Russian Foreign Minister Sergey Lavrov in Geneva on Friday, one week after US, NATO and European officials held multiple diplomatic meetings with Russian officials that ended without any significant breakthroughs.
Blinken said he would not be presenting a formal response to Russia's specific demands that NATO agree to never admit Ukraine -- which the US has said is a non-starter -- adding that it was "not clear what Russia's central demand is or not" and the effort now is to get at the heart of what those demands really are.
"I won't be presenting a paper at that time to Foreign Minister Lavrov," Blinken said. "We need to see where we are and see if there remain opportunities to pursue the diplomacy and pursue the dialogue, which again, as I said, is by far the preferable course."
At a news conference Wednesday marking the first year of his presidency, President Joe Biden predicted a Russian invasion of Ukraine, citing existential concerns by Russian President Vladimir Putin, even as he warned of significant economic consequences when such an incursion occurs.
But Biden suggested that a "minor incursion" would elicit a lesser response than a full-scale invasion.
"I'm not so sure he is certain what he is going to do. My guess is he will move in. He has to do something," Biden said, describing a leader searching for relevance in a post-Soviet world: "He is trying to find his place in the world between China and the West."
Zelensky, meanwhile, said Wednesday in a video address to the nation that he "sincerely believes" this year "will pass without a war" with Russia.
"Everything is under control and everything is going according to plan," Zelensky said. "Do not worry constantly what will happen in the future."
Standing alongside Blinken in Kyiv on Wednesday, Kuleba thanked the US for its support of Ukraine, while accusing Russia of trying to sow panic and stoke fear in Ukrainian institutions from the inside.
"We therefore need to apply all our efforts to prevent Russia from achieving that goal," he said. "Even before we reach to our arms, our efforts are focused on making sure that the situation in Ukraine stays stable and our financial system is strong and protected."
During his meeting with Zelensky on Wednesday, Blinken reiterated that Russia has two paths out of the current situation.
"There is the path of diplomacy and dialogue to try to resolve whatever differences there are peacefully through diplomacy," he said in his remarks to staff at the embassy. "Clearly the preferable path, clearly the most responsible path and the one that we would prefer, but there is also the path if Russia chooses to renew aggression, of conflict, confrontation and consequences for Russia."
Blinken said President Joe Biden had asked his team to "take stock" of the situation after intense negotiations with allies but also conversations with Russia, and to "reaffirm" the US' commitment to Ukraine.
"I strongly, strongly hope that we can keep this on a diplomatic and peaceful path, but ultimately, that's going to be President Putin's decision," he said.
The top US diplomat will later travel to Berlin to meet with his German counterpart to discuss efforts to deter further Russian aggression against Ukraine, before Blinken meets on Friday with Lavrov.
Blinken and Lavrov plan to discuss Russia's military build-up and its demands for security guarantees, in what will be the first high-level meeting between Russia and the United States since the diplomatic talks last week.
Russia has now deployed more than 127,000 troops near Ukraine, transferred more Iskander operational-tactical missiles to the border, and increased its intelligence activity against the country, according to the Ukrainian Defense Ministry's latest intelligence assessment that was shared exclusively Tuesday with CNN.
The Kremlin has continued to deny it is planning an attack, while demanding that the US and its Western partners rule out further NATO eastward expansion, guarantee that Ukraine would never join the block, and prevent NATO from establishing military bases in post-Soviet countries.