WASHINGTON, Jan 13 - A senior US official warned Thursday that the "drumbeat of war is sounding loud" following a week's worth of diplomacy between the West and Russia that wrapped up Thursday, CNN reported.

The effort ended without clear breakthroughs over the tens of thousands of Russian troops amassed on the Ukrainian border, leaving prospects for future diplomacy and de-escalation in doubt as Russian officials suggested they could soon turn to military options.

Both US and Russian officials sounded a pessimistic note over the talks following Thursday's meeting in Vienna at the Organization for Security and Cooperation in Europe (OSCE). It was the third session that capped a week of intensive meetings that the United States and its NATO allies hoped could spur Russia to pursue a path of "de-escalation and diplomacy" rather than mobilizing the tens of thousands of Russian troops whose presence has swelled along Ukraine's borders.

But Russian officials reacted with frustration and impatience coming out of the meetings, suggesting they were poised to abandon discussions over the US and NATO's refusal to entertain Moscow's key demands: A guarantee that Ukraine will never be permitted to join NATO and that the alliance roll back its expansion in Eastern Europe. The US and its NATO allies have repeatedly said such proposals from Moscow are non-starters.

Russian Deputy Foreign Minister Sergey Ryabkov suggested the talks had reached "a dead-end or a difference in approaches" because the US and NATO would not address Moscow's demands about Ukraine never joining NATO, he said, according to Russian state media TASS. Ryabkov said he didn't see a reason for the two sides to continue talks, even though the US has suggested they would continue beyond this week.

Following Thursday's session, the US Ambassador to the OSCE Michael Carpenter told reporters that the "drumbeat of war is sounding loud and the rhetoric has gotten rather shrill.”

"We have to take this very seriously," Carpenter said of the massing of Russian troops along the border with Ukraine. "We have to prepare for the eventuality that there could be an escalation."

The diplomatic efforts this week -- which included separate sessions between Russia and the US, NATO and the OSCE -- were aimed at pulling back Russia from a potential invasion of Ukraine. But Russia did not commit to pulling back the more than 100,000 troops now along the border, and the Russian military conducted live-fire exercises along the border this week as the talks were ongoing. (om/ez)