US-led NATO member countries are putting their forces on standby and reinforcing the deployment of weaponry in eastern Europe amid escalating tensions between Russia and the US over Ukraine.

In a statement on Monday, NATO secretary general, Jens Stoltenberg, welcomed the move, adding that the military alliance “will continue to take all necessary measures to protect and defend all allies, including by reinforcing the eastern part of the alliance.” “We will always respond to any deterioration of our security environment, including through strengthening our collective defence,” he stated.

The New York Times also reported on Monday that the US President Joe Biden was considering sending thousands of troops, as well as ships and fighter jets, to NATO allies in the region.

A number of NATO allies have made announcements regarding current or upcoming deployments in recent days, pointing to heightened tensions with Russia.

Denmark is sending a frigate to the Baltic Sea and deploying F-16 war planes to Lithuania, the NATO statement said.

Spain is sending ships to join NATO's standing maritime force and considering sending fighter jets to Bulgaria.

France was ready to send troops to Bulgaria, it added.

Moscow was quick enough to hit back at NATO’s announcement, warning the alliance that Russia will “respond appropriately” if US boosts troops in Eastern Europe and the Baltic countries.

Russian lawmaker Andrei Kartapolov, who heads the Russian parliament's defense committee, raised the alarm over the alliance’s expansion in the eastern Europe and called on the US not to fuel tensions.

Meanwhile, in an attempt to improve NATO’s military position in eastern Europe, the US also gave permission to three fellow-NATO member states of Lithuania, Latvia and Estonia in the Baltic region to send US-made missiles and other armaments to Ukraine.

The developments came as the US Secretary of State Antony Blinken yesterday said the US and its European allies are prepared to make a “united response” against Russia if it invades Ukraine.

The US, its NATO allies, and Ukraine have accused Moscow of amassing troops near Ukraine's border for a possible invasion.

However, Russia denies the allegations and says that the deployments are defensive in nature.