On May 8, the British Royal Navy destroyer HMS Dragon sailed from the naval base at Portsmouth on an urgent mission — to find and follow the Russian aircraft carrier Kuznetsov and six accompanying vessels steaming through the English Channel.

“A Russian task group of this size has not passed by our shores in some time,” said Rex Cox, Dragon’s captain.

True, the Russian navy has been more active in recent months. Moscow annexed Ukraine’s Crimean Peninsula with its strategic ports and asserted itself with troop, ship and warplane deployments along the frontier between Russia and the North Atlantic Treaty Organization.

That’s important to the Kremlin because, historically, Russia has struggled to maintain warm-water ports. Seizing Crimea helps ensure Moscow’s access to ice-free waters for commercial and military shipping.

But Russia’s busy fleet schedule masks an underlying seagoing weakness. Moscow’s warships are old and unreliable. Yet the government is finding it increasingly difficult to replace them with equally large and powerful new vessels.

Russia is a geriatric maritime giant surrounded by much more energetic rivals.

In the final years of the Cold War, the Soviet Union was determined to match the mighty U.S. Navy on the high seas. Moscow funded the construction of its first three full-size aircraft carriers in the late 1970s and 1980s — the non-nuclear Kuznetsov and a sister ship, plus a nuclear-powered vessel. The United States then possessed 15 large aircraft carriers, most of them nuclear-powered. After post-Cold War force cuts, today the United States has 10 nuclear flattops plus another nine small carriers.

The Soviet Union’s collapse dashed Moscow’s naval expansion plans. The Russians managed to finish paying the Ukrainian shipyard to complete Kuznetsov. But there was not enough money for the other two flattops. Today, a new aircraft carrier can cost billions of dollars.

Commissioned in 1991, Kuznetsov was Russia’s last new large warship. In the past 23 years, Moscow has managed to complete a few new submarines and small frigates and destroyers at its main Sevmash shipyard, on the North Atlantic coast. But many of Russia’s current naval vessels — and all its large vessels — are Soviet leftovers.

They’re outdated, prone to mechanical breakdowns and wickedly uncomfortable for their crews — especially compared to the latest U.S., European and Chinese ships. Washington alone builds roughly eight new warships a year, including a brand-new nuclear carrier every four or five years.

When Moscow moved to annex Crimea in March, the U.S. Navy promptly sailed its new flattop USS George H.W. Bush into the eastern Mediterranean to reassure NATO governments. Bush‘s battle group included no fewer than 60 high-tech warplanes and several of Washington’s modern Arleigh Burke-class destroyers, armed with missiles and guns for fighting planes, submarines and other ships.

In response, the Kremlin sent in Kuznetsov. The aging carrier — much smaller than Bush — carried a dozen or so Sukhoi fighters. Her six escorts included just a single heavily-armed vessel, the Soviet-vintage nuclear cruiser Pyotr Velikiy. The other five ships included one small amphibious landing ship plus three support tankers and a tugboat.

The tugboat was along for a good reason. On the few occasions when Kuznetsov leaves port, she often promptly breaks down. In 2009, a short circuit sparked a fire that killed one seaman aboard the rusting vessel.

Kuznetsov shadowed Bush in the Mediterranean for a few weeks, then returned home to northern Russia through the English Channel in early May. That’s when Dragon found her. For a more enduring presence in the Mediterranean, the Kremlin deployed one relatively modern destroyer, to reinforce Russia’s small existing Mediterranean flotilla.

Kuznetsov doesn’t have many years left in her. Her boilers are “defective,” according to the trade publication Defense Industry Daily. Yet when she goes to the breakers to be dismantled, Moscow could find it impossible to replace her. For one, the shipyard that built all the Soviet carriers now belongs to Ukraine. It lies just outside of Crimea, and Russian forces did not manage to seize it.

Moreover, Ukraine is still the exclusive supplier for many of the heavy components, including engines and gears, for Russia’s warships — even the ones Russia builds in its northern shipyard. With the continuing tense stand-off, Kiev recently banned arms sales to Moscow.

Russia’s attempts to revitalize its domestic shipbuilding industry have not gone smoothly. In 2005, India inked a nearly $1-billion deal with Russia for a rebuilt Soviet-era small flattop. Russia’s work on Vikramaditya was so poor, however, that she suffered a near-total breakdown shortly after her purported completion in 2012.

India finally accepted Vikramaditya this year — after the total cost of her refurbishment had nearly tripled to $2.3 billion. If Russia can’t even remodel an existing warship, imagine the difficulties it would face designing and building a big new ship from scratch.

Moscow knows its navy is in trouble. It seized on an extreme solution in 2011 — importing ships, technology and expertise from France. Russia signed a contract for two French Mistral-class helicopter carriers. Each ship costs more than $1 billion.

The plan was for Russian shipyards to help construct the vessels. “The purchase of Mistral shipbuilding technology will help Russia to grasp large-capacity shipbuilding,” Admiral Vladimir Vysotsky, chief of the navy at the time. “It is important for construction of ships like the future ocean-going class destroyer and later an aircraft carrier.”

Unsurprisingly, the Russian yards have proved incapable of handling intensive construction. In 2013, the Kremlin asked France to take over the bulk of the work. When Russia annexed Crimea, Paris threatened to cancel the ship deal. But France was reluctant to give up billions of dollars in revenue. Russia’s first French-built ship is nearing completion and could sail to Russia late this year.

But buying two ships from France will do little to reform Russia’s shipbuilding industry if Russian workers aren’t directly involved in building them. Now deprived of the Ukrainian-made parts, Russia’s shipbuilding industry is arguably in worse shape than it was just a few months ago.

That bodes poorly for Russia’s future as a naval power. Dragon’s interception of Kuznetsov could prove to be a turning point. In coming years, large Russian warships could become a very rare sight.

The implications are serious for Moscow’s influence in the world — and for its ability to win a war against a maritime foe.

PHOTO (TOP): A Russian nuclear submarine lies at Zvezda (Star) factory before being dismantled in Bolshoi Kamen, 90 km (56 miles) east of Vladivostok, April 26, 2010. REUTERS/Yuri Maltsev

PHOTO (INSERT 1): A man walks past a Russian nuclear submarine at Zvezda (Star) factory in Bolshoi Kamen, 90 km (56 miles) east of Vladivostok, April 26, 2010. REUTERS/Yuri Maltsev

PHOTO (INSERT 2): The Russian nuclear-powered cruiser Pyotr Veliky or Peter the Great at the port of La Guaira outside Caracas, November 27, 2008. REUTERS/Jorge Silva

PHOTO (INSERT 3):The Russian aircraft carrier Admiral Kuznetsov underway in the Mediterranean Sea, January 7, 1996. REUTERS/U.S. Navy/Handout

PHOTO (INSERT 4) The Mistral-class helicopter carrier Vladivostok is seen at the STX Les Chantiers de l’Atlantique shipyard site in Saint-Nazaire, western France, April 24, 2014. REUTERS/Stephane Mahe

PHOTO (INSERT 5): Russian President Vladimir Putin seen through the glass of C-Explorer 5 submersible after a dive in the Gulf of Finland in the Baltic Sea, July 15, 2013. REUTERS/Aleksey Nikolskyi/RIA Novosti/Kremlin