The United States on Wednesday rejected Russia's demand to bar Ukraine from NATO and said it believed Moscow was ready to invade but offered what it called a new path out of the crisis.

Secretary of State Antony Blinken said Washington had set out to Moscow a "serious diplomatic path" to resolve the confrontation, in a private letter to the Russian government.

However, he stressed, "We make clear that there are core principles that we are committed to uphold and defend, including Ukraine's sovereignty and territorial integrity, and the right of states to choose their own security arrangements and alliances."

Blinken was addressing the media soon after his deputy Wendy Sherman said the United States remained convinced that Putin was poised to use force against Ukraine by mid-February.

He said the letter emphasized that Kyiv can choose its own allies, rebuffing Moscow's demand for a pledge that Ukraine will not join the NATO alliance.

Antony Blinken
US Secretary of State Antony Blinken Photo: POOL via AFP / Kay Nietfeld

Blinken told reporters that the letter would not be made public, "because we think that diplomacy has the best chance to succeed."

He said he would speak to Russian Foreign Minister Sergei Lavrov in the coming days for its response to the US stance.

In the missive, he said, "We make clear that there are core principles that we are committed to uphold and defend, including Ukraine's sovereignty and territorial integrity, and the right of states to choose their own security arrangements and alliances."

"We've addressed the possibility of reciprocal transparency measures regarding force posture and Ukraine, as well as measures to increase confidence regarding military exercises and maneuvers in Europe."

The letter, which was coordinated with Kyiv and US allies in Europe, the United States, also opens the door to advancing arms control talks with Russia over the issue of strategic missiles and nuclear weapons positioned in Europe.

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