Over the sandbanks and marshes of northern Latvia, battle cries rang out late last month as U.S. and Latvian troops stormed a mock-up urban street, a training exercise one officer described as a “Stalingrad-type scenario” for soldiers more used to peace-keeping or fighting rural insurgents. After an €80,000 anti-tank missile and a volley of mortar and artillery fire launch the drills, a U.S. Black Hawk transports Latvian soldiers into the war games scenario, where they go house-to-house searching for a high-value target.

Not far away in the Latvian capital of Riga, officials were getting to work in the newly-inaugurated NATO Strategic Communications Center of Excellence, a hub aimed at countering information warfare by enemies of the 28-member military alliance.

The endeavors are at opposite ends of the tactical spectrum, but reflect the challenges presented by the new hybrid warfare which analysts say is the Kremlin’s modus operandi under President Vladimir Putin. While Russian troops openly went into Crimea this year to annex it from Ukraine, some of Russia’s neighbors are grappling with more subtle meddling and mind games.

“NATO must be flexible,” Latvian Defense Minister Raimonds Vejonis tells TIME, citing economic coercion, propaganda warfare and military intimidation along Russia’s Baltic borders as some of the new threats to emerge in the past year.

“During the last 65 years after the Second World War it was calm and silent in Europe… now the situation has changed this year due to Russian activities in Ukraine. We must be ready to adapt to the new situation, and ready to react to new geopolitical challenges in Europe.”

NATO members are beefing up their forces in eastern Europe as a result. Earlier this year 600 U.S. troops from the 173rd Airborne Brigade deployed to Poland, Lithuania, Estonia and Latvia and this week, U.S. tanks returned to Latvian soil for the first time since the Second World War. Joint military exercises have increased in size and frequency. At a NATO summit last month, leaders pledged increased funding for cyber and information warfare units, while also announcing the formation of a Rapid Reaction Force which could deploy to allied nations within days.

Analysts say this is a good start, but there is concern that NATO needs to send a stronger signal that any Russian military intervention – not just a overt invasion – would provoke Article Five, by which an attack on one member demands reaction from all 28.

“This is time for NATO to be crystal clear,” says Matthew Bryza, a former US diplomat now working for the Estonia-based International Center for Defense Studies. “If you use military force in the Baltic states, there will be consequences, there will be war. It needs to be that clear.”

A return to the conventional warfare and military muscle-flexing of the past appears to be the easy part. The generation of military minds overseeing NATO’s transformation is steeped in Cold War history.

“My father was in the military, I grew up in Germany, and was in Berlin when the Berlin Wall fell, so (the context) is certainly not lost on my generation,” says LTC Robert ‘Todd’ Brown, a battalion commander of the 173rd Airborne Brigade who designed the urban war games.

The resonance is even stronger in the Baltic states, which spent five decades as part of the Soviet Union. “We know what occupation means,” says Colonel Martins Liberts, Commander of the Latvian Land Forces. He says the joint exercises illustrate the changing focus from peace-keeping and nation-building abroad to multinational forces protecting home soil from conventional threats.

More than 100 of his troops are taking part in the live-fire exercise with U.S. troops over the sand dunes and marshes of Adazi Military Base about an hour’s drive from Riga. After an €80,000 anti-tank missile and a volley of mortar and artillery fire launch the drills, a U.S. Black Hawk transports Latvian soldiers into the war games scenario, where they go house-to-house searching for a high-value target. The street may be made from plywood, and their enemy cardboard silhouettes with balloons pinned to their chests, but the message the Latvians want to send Russia is very real.

“It is a strong political signal to Russia that we are part of NATO [and] Article Five will be enforced if it is be needed,” says Defence Minister Vejonis.

From Russia’s point of view, the war games are another example of NATO creeping closer to its borders, measures it feels are unnecessary and provocative. But Moscow has not held back from its own military posturing: since the start of this year Latvia has detected 170 cases of Russian fighter jets coming close to their border. That compares with about 50 such cases in the previous decade. Russian war ships and submarines have also upped patrols in the Baltic Sea.

The country’s neighbors have also been affected. Last week, Lithuania accused Russia of violating international law after its border guards seized a Lithuanian fishing vessel and its 30 crew whom they accused of illegally trawling for crab in Russian waters. Estonia – which in 2007 blamed Russia for a massive cyber attack on government websites – is currently locked in dispute with Moscow over a security official which its government says was kidnapped on its territory in a cross-border raid last month.

It is these kinds of subtle provocations that Bryza thinks NATO should respond to more forcefully, or risk giving Putin the confidence to escalate the meddling. Bryza also advocates permanent NATO bases on eastern European soil – a move also suggested in the past by Poland and Estonia, but one which would violate a historical NATO-Russia pact.

For now, Latvian officials say they are happy with the Rapid Reaction Force announced in September, but are keen to see it and other defensive measures come into force quickly. “We have been quite good in declarations so far, but implementation is important,” says Andrejs Pildegovics, State Secretary for Foreign Affairs.

“Seeing how deep Russia’s involvement in the war with Ukraine has been, seeing these militaristic statements by Russian leaders, seeing this speculation about how capitals can be conquered in the neighborhood – we think it should be really rapid.”

Contact us at letters@time.com.