Russia said on Wednesday that it would not be intimidated by US military reinforcements in Europe, as tensions over Moscow's military operation in Ukraine continue to rise.

"I think that those who propose such solutions are under the illusion that they will be able to intimidate Russia, somehow restrain it -- they will not succeed," Deputy Foreign Minister Sergei Ryabkov told reporters.

"The security of countries where additional contingents will appear will not be strengthened. The prospect of stabilization will be distant. Risks will increase," he added. He said Russia would respond.

"We have the capabilities and resources," Ryabkov added, threatening retaliation. "Now what is happening will certainly lead to compensatory measures on our part."

NATO leaders were set to invite Finland and Sweden to join the alliance on Wednesday after Turkey dropped its objections, as the alliance sought to strengthen its defenses at a summit dominated by Moscow's military operation in Ukraine.

NATO considers Russia's "military build-up’ challenge

In a statement issued on Wednesday, NATO stated that Russia's "military build-up" in the Baltic, Black, and the Mediterranean Sea regions poses a threat to its interests.

"Moscow’s military build-up, including in the Baltic, Black, and the Mediterranean Sea regions, along with its military integration with Belarus, challenge our security and interests," the declaration read.

NATO also stated that it faces "systemic competition" from China, which challenges the alliance's values and interests. Furthermore, NATO stated that deepening the Moscow-Beijing strategic partnership is a challenge.

Read next: Biden: US to strengthen its presence and allies in Europe

Earlier on Wednesday, during the opening of the summit, Biden met with NATO Secretary-General Jens Stoltenberg in Madrid where he said that “NATO is strong and united, and the steps we’re taking during this summit, we’re going to further augment our collective strength.”

Biden also stated that the US is funding a permanent HQ in Poland, as well as sending two additional F-35 fighter jet squadrons to the UK, and further “air defense and other capabilities” are set for Germany and Italy.

“Today I’m announcing the United States will enhance our force posture in Europe and respond to the changing security environment as well as strengthening our collective security,” adding that “In Poland, we’re going establish a permanent headquarters, the US Fifth Army Corps, and strengthen the US-NATO interoperability across the entire eastern flank,” Biden announced. Rotational deployments of troops across the Baltics region will also be boosted according to POTUS.

Yesterday, a US official said that the US will announce new long-term military deployments across Europe in response to what he dubbed as "Russia's threat" during the NATO summit in Madrid.

According to National Security Advisor Jake Sullivan, "Specific announcements tomorrow on land, sea, and air of additional force posture commitments over the long term" will be made.

The forces will be focused on the Baltics, the Balkans, and NATO's eastern flank bordering Russia. NATO will issue a "historic set of deliverables... on the issue of force posture," according to Sullivan.

He emphasized that the alliance's increased presence in Europe is not just a reaction to the immediate instability caused by Russia's military operation in Ukraine and the ensuing war, which is now in its fourth month, but also to a "long-term change in the strategic reality."