A few weeks ago, I reported on a series of attempted breaches of security as Russian jets headed toward U.K. airspace. Jets were scrambled from all over the country and the Russian bombers changed course as if nothing had ever happened. Earlier still, a Russian ship steamed on past England’s shores, a bit close for comfort. It’s now gone up a notch, as 800 British troops have just been deployed to Estonia to deter against Russia’s aggressive tactics in Eastern Europe.

The first wave of troops deployed from RAF Brize Norton in Oxfordshire on March 17th. This wave consisted of 120 soldiers from the 5th Battalion, the Rifles, who landed at the Ämari Air Base, 25 miles southwest of the Estonian capital, Tallinn. They were welcomed by Estonia’s defense minister, Margus Tsahkna, who recognized that this is the largest deployment of Western troops anywhere in the region since the Cold War. The first group represents an advance party and will set up headquarters in the country to prepare for the others’ arrival next month.

French and Danish forces have also deployed to provide “a proportionate, defensive, and combat-capable force to defend our NATO ally and deter any form of hostile activity against the alliance,” the ministry of defense said. Fairly strong words and even stronger actions from the U.K., which has troops deployed all around the world and could probably have done without this.

Britain is once again taking a leading role in the Estonia battle group while other NATO members are deploying forces to Latvia, Lithuania, and Poland as part of NATO’s Enhanced Forward Presence battalion.

Stacked up ready to go by ferry to Estonia are over 300 British vehicles, including Challenger 2 tanks, Warrior tracked vehicles, and AS-90 self-propelled artillery pieces. That’s a lot of hardware and troops, and a clear statement by the U.K. that Putin’s antics will not be tolerated.

NATO has shown concern lately with Russian behavior in Eastern Europe. Putin’s regime has been overtly aggressive to their neighbours, who are genuinely worried.

Since the annexation of Crimea and with the ongoing conflict in the Donbass region of Ukraine, many former Iron Curtain states fear encroachment from their former imperial master. They are constantly looking over their shoulders as Russia eyes up potential prey.

Earlier this year, in January, both the Germans and the Belgians tipped up in Lithuania, a reaction to the fear of a Soviet invasion near the Russian enclave of Kaliningrad. These troops bolstered the limited assets that were already deployed.

British Prime Minister Theresa May confirmed the U.K. would help out any of our allies, such as Estonia or Lithuania, in the event that Russia got carried away. She also said that the U.K. took the country’s commitment to NATO seriously.

Under the terms of Article 5 of NATO’s charter, if one member state is invaded, all the other nations are obliged to come to their aid. It’s an insurance policy for smaller nations who may not have the capacity to defend their own borders from the larger threats—a way of stopping the smaller nations from being bullied by their larger neighbours.

There are growing fears about the commitment of NATO’s largest military power, the U.S., after Donald Trump suggested he may not come to an ally’s defense unless they contribute more to the organization’s budget. He later vowed “strong support” for NATO during his first visit to the headquarters of U.S. Central Command in Florida in February.

NATO guidelines say member states should spend at least two percent of their GDP on defense, but only five of the 28 in the alliance—the U.K., Greece, Poland, the U.S., and Estonia—currently meet the target. It’s a tough world out there, and some countries are suffering more than others.

It’s a situation I will be following closely.