Russian officials said they are not optimistic after receiving responses Wednesday from the U.S. and NATO over demands made by Russia that NATO halt its eastward expansion. The U.S. and NATO did not reveal the content of the letters, but Secretary of State Antony Blinken confirmed the U.S. and its allies did not agree to curb its expansion but offered a path forward for negotiations with Moscow.

Secretary of State Antony Blinken: “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.”

Meanwhile, the military buildup continues on both sides of the Russia-Ukraine border, where some 100,000 Russian troops have been massed for weeks. Earlier this week, the U.S. put 8,500 troops on “heightened alert” to deploy to the region if needed.

In Congress, top progressive Democrats Pramila Jayapal and Barbara Lee called on the Biden administration Wednesday to pursue diplomacy amid the escalation tensions, warning “there is no military solution” to the crisis.