TAPA, ESTONIA - French soldiers in Tapa military base.TAPA, ESTONIA - French soldiers in Tapa military base.

NATO troops are on alert just 70 miles away from the Russian border and an hour away from the capital of the country.

The NATO military alliance has increased its presence at the Tapa military base in central Estonia since Russia annexed the peninsula. Since early February, when Moscow deployed about 100,000 troops closer to Ukraine, there have been more signs of political tensions.

Simon Worth, commanding officer of the U.K.'s Royal Tank Regiment, said that the situation in Ukraine gave them greater focus and clarity.

The U.K. is the leader of NATO's presence at this military base and it has contributed with the highest number of soldiers.

It is a defensive presence here, but we thought it would be important to assure our partners.

The U.K. could decide to keep these troops in the region.

About 200 soldiers from France andDenmark have been sent to this base. There are 4,000 troops on the ground with the addition of 2,000 Estonian soldiers.

The Tapa military base is now at full capacity, with some of the soldiers having to sleep in tents.

Colonel Dai Bevan, commander of NATO's Enhanced Forward Presence in Estonia, told CNBC that their day-to-day involves constant training.

To make sure that we are prepared to respond to any threat to the NATO area.

Defense and military officials in Estonia don't think that Russia is going to attack any NATO country, partly because Russian troops have been slow to make inroads in Ukraine. The defense alliance is on high alert over potential cyber attacks and misinformation.

NATO has refused to send soldiers to Ukraine because they fear that it would lead to a new world war. Equipment has been sent to the Ukrainian forces and it is also reinforcing its presence in eastern Europe.

Poland has the highest number of NATO troops at 10,500. The battlegroup is led by the United States.

More planes and ships have been sent to eastern Europe by the defense alliance.

NATO is likely to send new troops to Bulgaria, Hungary, Romania and Slovakia, according to Secretary-General J ens Stoltenberg.

NATO's posture will be strengthened with major increases in the eastern part of the alliance, according to NATO Secretary General Jens Stoltenberg.