CNN — NATO sees no sign that Russia is pulling its forces back from the border with Ukraine, NATO Secretary General Anders Fogh Rasmussen said Tuesday, despite Moscow's claim of a partial pullback.
"Unfortunately I cannot confirm that Russia is withdrawing its troops," Rasmussen said at the opening of a two-day meeting of NATO foreign ministers in Brussels, Belgium.
"This is not what we're seeing. And this massive military buildup can in no way contribute to a de-escalation of the situation."
Concerns are high that Russia, which U.S. officials last week said had about 40,000 troops near the frontier, might seek to enter eastern Ukraine, after it annexed Ukraine's Crimea region last month.
Russian President Vladimir Putin told German Chancellor Angela Merkel on Monday that he'd ordered a withdrawal of some Russian troops from his country's border area with Ukraine, Merkel's office said.
The news prompted U.S. State Department spokeswoman Jen Psaki to say Monday that if the reports were accurate, "it would be a welcome preliminary step."
But Rasmussen appeared to quash hopes that the situation might be easing with his remarks Tuesday.
He said the NATO foreign ministers would discuss options to boost their collective defense capability, including enhanced military exercises and updated defense plans, in addition to the stepped-up NATO air surveillance already in place above Eastern European nations.
"Defense starts with deterrence, so we will take the necessary steps to make it clear to the world that no threat against NATO allies will succeed," Rasmussen said.
He said that Russia's actions are unacceptable and that they will discuss what cooperation with Russia is still appropriate. "We cannot go on doing business as usual," he said.
But, Rasmussen stressed, the alliance still seeks a peaceful solution to the crisis.
"I don't think anybody honestly would like to see a military confrontation in Europe," he said, adding that "the right way forward is the diplomatic and political path."
He urged Russia to pull back its forces from the border area and engage in dialogue with the interim Ukrainian government.
Russian state media reported Monday that one Russian infantry battalion was being moved from the border area to its base deeper into Russia. A battalion would typically number several hundred troops.
Psaki also urged Russia on Monday to talk with the government in Kiev to de-escalate the situation. Moscow does not recognize Ukraine's new government, saying ousted President Viktor Yanukovych was removed in an unconstitutional coup.
Russia annexed Ukraine's Crimean peninsula last month amid the political upheaval that followed the ouster of the pro-Moscow Yanukovych, sparking the most serious East-West crisis since the Cold War ended.
Gazprom hikes natural gas price
Russian energy giant Gazprom announced a sharp increase Tuesday in the price it charges Ukraine for natural gas, in a move that will heighten pressure on the interim government in Kiev.
Starting Tuesday, Ukraine will be charged $385.50 per 1,000 cubic meters of gas, up from the previous rate of $268.50, Russian state news agency RIA Novosti quoted Gazprom Chief Executive Alexei Miller as saying.
The move ends a discount that was agreed to before Yanukovych was ousted in February after months of street protests.
The gas price hike will only increase the pressure on Ukraine's interim government as it seeks to stave off economic collapse.
Ukraine, which is heavily reliant on Russia for energy, is also $1.7 billion in arrears in its payments for gas already supplied, Miller said, according to RIA Novosti.
The International Monetary Fund last week agreed to lend Ukraine up to $18 billion over the next two years in return for a package of reforms, including to its energy market.
Kiev has been running dangerously low on cash to pay for imports and service its debts since the ousting of Yanukovych, which killed off a $15 billion financial lifeline from Russia.
CNN's Boriana Milanova and Marie-Louise Gumuchian contributed to this report.