Moscow/Washington - Russia said on Thursday it was clear the United States was not willing to address its main security concerns in their standoff over Ukraine, but both sides kept the door open to further dialogue.

The United States and NATO submitted written responses on Wednesday to Russia's demands for a redrawing of post-Cold War security arrangements in Europe since it massed troops near Ukraine, prompting Western fears of an invasion and new U.S. pledges of defense support.

Kremlin spokesman Dmitry Peskov said Moscow needed time for review and would not rush to conclusions, but that U.S. and NATO statements describing Russia's main demands as unacceptable did not leave much room for optimism.

"Based on what our (U.S. and NATO) colleagues said yesterday, it's absolutely clear that on the main categories outlined in those draft documents ... we cannot say that our thoughts have been taken into account or that a willingness has been shown to take our concerns into account," Peskov said. "But we won't rush with our assessments."

The nuanced Kremlin reaction showed Russia was not rejecting the U.S. and NATO responses out of hand or closing the door to diplomacy. Washington says it and its allies hope Russia will study their responses and come back to the negotiating table.

Russia's foreign ministry said the best way to reduce tensions was for NATO to remove forces from eastern Europe, but also sought to quash fears of an invasion. U.S. officials say President Vladimir Putin has not yet decided whether to invade.

"We have already repeatedly stated that our country does not intend to attack anyone," said Alexei Zaitsev, a Russian foreign ministry spokesman. "We consider even the thought of a war between our people to be unacceptable."

Invasion likely next month, tells US

US President Joe Biden has warned there is a "distinct possibility" Russia might invade Ukraine next month, the White House says.

Russia meanwhile says it sees "little ground for optimism" in resolving the crisis after the US rejected Russia's main demands.

The US president made the comments in a telephone conversation with Ukrainian President Volodymyr Zelensky on Thursday.

"President Biden said that there is a distinct possibility that the Russians could invade Ukraine in February," White House National Security Council spokesperson Emily Horne said.

Nord Stream 2

On Thursday, the US threatened to halt the opening of a key pipeline that would send Russian gas to Western Europe if Russia invades Ukraine.

Nord Stream 2 would run from Russia to Germany, and on Thursday officials in Berlin said the project could face sanctions if Russia attacks.

Western allies say they will target Russia's economy if it invades, and the latest comments signal a hardening of their stance.

The 1,225km (760-mile) pipeline took five years to build and cost $11bn (£8bn). The energy project, which would run under the Baltic Sea, is designed to double Russia's gas exports to Germany.

But as yet it has not started operating, as regulators said in November it does not comply with German law and suspended its approval.

Four-way Paris talks

Russian and Ukrainian negotiators agreed that a permanent ceasefire in eastern Ukraine must be observed "unconditionally" following hours-long talks in Paris on Wednesday.

Ukrainian negotiator Andriy Yermak called the renewal of the Normandy Format talks -- first held after Russia's 2014 invasion of Crimea -- a "very positive signal" and the first such substantive agreement since the end of 2019.

Kozak and Yermak said the talks would resume in about two weeks in Berlin.

Looming threats

Putin, who has not spoken publicly on the crisis for weeks, has warned of an unspecified "military-technical response" - something defence analysts say could relate to missile deployments - if Russia's demands are ignored.

A senior Russian foreign ministry official said a nuclear missile crisis between Moscow and Washington was unavoidable without measures to ensure restraint and predictability.

Biden has said he will not send U.S. or allied troops to fight Russia in Ukraine but NATO has said it is putting forces on standby and reinforcing eastern Europe with more ships and fighter jets.
-BBC, Reuters