Washington — The Russian submarine fleet has returned to the North Atlantic with such gusto that NATO sub commanders are reporting "more activity from Russian submarines than we've seen since the days of the Cold War," according to a top NATO admiral.

Royal Navy Vice Adm. Clive Johnstone, speaking aboard a Spanish frigate at the end of last month, told the defense analysis group IHS Janes that the alliance is also seeing "a level of Russian capability that we haven't seen before."

Russia's submarine program froze as funds dried up following the collapse of the Soviet Union.

Recently, however, Russia has commissioned two new types of subs, including a nuclear-powered attack variant and a nuclear-powered ballistic missile class.

According to Janes, they also have started modernizing older submarines as well.

Johnstone said that with these upgrades and newer boats, Russia is "freer to operate" beneath the waves, as the new technology and an increase in spending has greatly increased Russia's capabilities.

Johnstone also added that Russian submarine crews are more professional in years past, something that has also raised concern within the alliance.

While Russia's revamped sub fleet is certainly a concern for the west, what worries Johnstone is the lack of openness about Russia's strategic and operational objectives. The admiral added that the Russians have yet to invite a NATO representative to one of their exercises in the last two years — something that NATO does regularly.

"I'm not saying we want to be part of everything and I'm not saying that Russians are the 'Great Bear' or that they're the enemy, but what we've got to do in this very complicated maritime environment is take out the uncertainty and reinforce the certainty," Johnstone said.

The admiral added that while Russian activity off NATO ports and in NATO water space was confounding, "it's hard not to draw a certain set of conclusions."

Recently, the United States has monitored Russian submarines and surface ships patrolling around under sea fiber optic cables.

While the Russians' intentions are unclear, tapping underwater communication lines is an old Cold War tactic revolutionized by the U.S. Navy in a series of spy missions that began in 1970.

In November, the United Kingdom had to request additional support from France to help detect what they thought was a Russian submarine spying off the coast of Scotland on one of England's new nuclear missile systems.

Russia's renewed sub activity has altered how NATO now approaches its maritime capabilities, according to Johnstone.

"You're starting to see nations who in the past have prioritized to have submarines in the Gulf or the eastern Mediterranean now looking to reinvest back into capability in the Atlantic," Johnstone said.

Even though Russia sub activity has skyrocketed, Russia has only just started introducing new boats into its fleet and most NATO countries are operating their fleets at half of what they were during the Cold War.

The U.S. Navy operates a number of sub variants, including the newer nuclear-powered fast-attack Virginia Class.

Bolstering NATO allies in Europe

The Obama administration wants to boost military spending in Europe next year to stockpile heavy weapons, armored vehicles and other military equipment in eastern and central Europe, a substantial expansion of efforts to counter a resurgent Russia. 

The proposed $3.4 billion initiative will permit the Pentagon to keep the equivalent of a 4,000-soldier armored brigade in the region at all times on rotational deployments, though no troops will be formally based there, officials said.

“We asked for the amount we think we’ll need” to counter “the Russian challenge in Europe,” Defense Secretary Ashton Carter told reporters Wednesday during a visit to a naval weapons research facility in China Lake, north of Los Angeles.

The proposal, part of the Pentagon’s $583 billion budget request, must be approved by Congress. The administration is expected to unveil the budget next week.

The administration also plans to double spending for the battle against Islamic State.

American aircraft have conducted so many airstrikes in Iraq and Syria since mid-2014 that the Pentagon is running out of smart bombs and missiles; it will seek $1.8 billion next year to buy 45,000 more.

But in a speech Tuesday, Carter listed Russia as the primary threat to U.S. interests, citing President Vladimir Putin’s annexation of Crimea and military operations in eastern Ukraine that potentially threaten the Baltic nations.

“We’re reinforcing our posture in Europe to support our NATO allies in the face of Russia’s aggression,” Carter told the Economic Club of Washington. “We haven’t had to worry about this for 35 years, and while I wish it were otherwise, now we do.”

The Pentagon plans to construct or refurbish maintenance facilities, airfields and training ranges in seven European countries: Bulgaria, Estonia, Germany, Latvia, Lithuania, Poland and Romania. All are members of the NATO alliance.

Except for Germany, all were under Soviet domination during the Cold War. Germany was divided into two countries, one pro-West and the other aligned with Moscow.

Many of the seven have pressed NATO and the U.S. for a greater presence since Russian forces seized Crimea in 2014 and began backing pro-Russian separatists in Ukraine with weapons and troops.

Russia has boosted defense spending dramatically over the last decade to modernize its military. It has used some of the new weapons, including ship-launched cruise missiles, to support its intervention in Syria on behalf of the country’s embattled president, Bashar Assad.

Pentagon officials, who spoke on condition of anonymity to discuss parts of the plan that have not been made public, conceded that several thousand U.S. troops spread across seven countries could not hold back the Russian Army should it decide to invade.

The expanded U.S. presence is meant to signal Moscow that the U.S. would come to the aid of its allies with additional forces in case of war and to reassure allies of American backing, the officials said.

It would take at least seven NATO brigades, including three with tanks and other armored vehicles, backed by artillery and combat aircraft, to prevent Russian forces from “the rapid overrun” of Latvia, Lithuania and Estonia, according to a study released this week by RAND Corp., a policy analysis organization.

Russian forces could reach Estonia and Latvia’s capital cities in less than 60 hours, the study estimated.

“Such a rapid defeat would leave NATO with limited options, all bad," the study said, noting that putting seven brigades in the region “while not enough to mount a sustained defense ... would fundamentally change the strategic picture as seen from Moscow.”

Estonia is the only NATO member other than the United States that last year spent at least 2 percent of its gross domestic product on defense, NATO said last month.

None of the money requested by the White House is earmarked for Ukraine, which is not in NATO.

The Pentagon has sent troops to train with Ukraine’s armed forces and provided the government in Kiev with nonlethal equipment.

But the administration has stressed it does not plan to go to war in Ukraine, and is relying on economic sanctions and diplomatic pressure to deter Russia from further involvement.

In a 1997 agreement meant to prevent a return to Cold War tensions, NATO and Moscow pledged not to station large numbers of forces on each other’s borders.

Pentagon officials say the proposed expansion does not violate that pledge because the troops will rotate in and out to multiple locations, even though the effect will be a constant presence.

During the Cold War, U.S. European Command stationed more than 200,000 U.S. troops in Germany and other NATO countries. It now has about 65,000 troops, including two combat brigades of about 3,500 soldiers each.

The Army has designated a brigade based at Fort Stewart, Ga., parts of which will rotate to Europe every year.

But the forces envisioned for Eastern and Central Europe will come from other Army units, the officials said.

David S. Cloud of the Tribune Washington Bureau (TNS) contributed to this report.