The president of Ukraine held a video call with 20 U.S. senators and members of Congress on Friday amid tensions with Russia, which recently stoked fears of a possible invasion by massing troops near Ukraine’s border.

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Ukrainian President Volodymyr Zelenskyy spoke with the senators and congressional representatives about the Russian troop buildup and the situation in his country’s war-torn east, according to Zelenskyy’s office. Russia-backed rebels have been fighting Ukrainian forces in eastern Ukraine since 2014.

A statement from the president’s office described “the importance of getting the United States involved in the process of a peaceful settlement” to the conflict in eastern Ukraine, an area known as Donbas.

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“Now, more than ever, it is not words that matter, but decisive actions,” the statement quoted Zelenskyy as saying. “My goal is to stop the bloodshed in the east of Ukraine. It’s impossible to imagine security in Europe without ending the war in Donbas.”

Zelenskyy and the lawmakers also talked about applying further sanctions pressure on Russia, Washington’s support of Kyiv’s “Euro-Atlantic aspirations” and Ukraine’s prospects for NATO membership.

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Russia and Ukraine have been locked in a bitter tug-of-war since Moscow annexed the Ukraine’s Crimean Peninsula in 2014 and threw its support behind the separatist insurgency that has since left more than 14,000 people dead.

A 2015 peace deal, brokered by France and Germany, ended large-scale hostilities in Donbas, but efforts to reach a political settlement of the conflict have failed so far.

Tensions between Russia and Ukraine reignited over the troop deployment near Ukraine’s border. Officials in Ukraine and the West feared it might indicate plans for an invasion, but the Kremlin has denied that intent.

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Instead, Moscow has accused Kyiv of its own troop buildup in the east, saying Ukrainian military could be planning to reclaim the rebel-held areas by force.

Russian President Vladimir Putin also has pressed the United States for guarantees that would preclude NATO from expanding east to Ukraine. The Western alliance and Ukraine have bristled at the demand.

During his call with the American lawmakers and senators, Zelenskyy said “not a single third country can have a say in Ukraine’s integration into NATO.”

“No agreements on Ukraine without Ukraine,” he said.