London - Coup attempts, cyberwarfare, assassination bids — Western officials say the GRU, Russia’s military intelligence agency, poses a growing menace around the world.

Increasingly alarmed by the agency’s foreign forays, Western nations are scrambling to protect themselves and to strike back against a shadowy organization British Prime Minister Theresa May calls “a threat to all our allies and our citizens.”

This week Britain charged two alleged GRU agents in absentia with the poisoning of former Russian spy Sergei Skripal and his daughter Yulia, who were left critically ill after being exposed to a Soviet-made nerve agent in the English city of Salisbury.

May said the attack was approved “at a senior level of the Russian state,” and vowed Britain would “deploy the full range of tools from across our national security apparatus in order to counter the threat posed by the GRU.”

Moscow denies any involvement, and Britain and its allies won’t find it easy to counter an organization with strong ties to the Russian leadership and a seeming disregard for international laws.

The GRU — formally named the Main Directorate of the General Staff of the Armed Forces — is one prong of Russia’s vast security and intelligence apparatus, and has been linked to a series of audacious and deadly operations around the world.

In the United States, 12 alleged GRU agents have been indicted for hacking the Democratic Party and Hillary Clinton’s campaign during the 2016 U.S. presidential election.

The investigative group Bellingcat has reported that a GRU officer was in charge of operations in eastern Ukraine, where Russia-backed separatists were fighting Ukrainian forces, when a Malaysian passenger airliner was shot down in July 2014, killing all 298 people aboard. Western officials have also linked GRU agents to an attempted coup in Montenegro in 2016.

Aglaya Snetkov, an expert on Russian security at University College London, says Russia has taken an increasingly assertive stance overseas in a host of ways since Moscow authorities grew concerned more than a decade ago at “what they saw as increased Western interference in (places like) Ukraine and Georgia.”

“The Russians are now using their intelligence services more actively, alongside all the other instruments they have in terms of influence — things like (TV channel) RT, party political meetings, increasing societal links, greater links with the diaspora abroad,” she said Friday.

“The intelligence guys are only one side of it.”

For Western countries, countering Russian interference is equally complex.

U.K. prosecutors say they have enough evidence to charge the two suspects in the attack on Sergei Skripal, a former GRU officer who had betrayed the service by spying for Britain. But they are unlikely to face a British trial, since Russia will not extradite its citizens to be prosecuted abroad.

Instead, Britain is trying to squeeze Moscow through diplomatic, economic and covert channels.

After the Skripals were poisoned March 4, Britain and more than two dozen other countries expelled a total of 150 Russian spies working under diplomatic cover. Russia kicked out a similar number of those countries’ envoys.

Britain gave its border guards new powers to stop people they suspected of being spies, and introduced a version of the United States’ Magnitsky Act, which allows authorities to ban or seize assets of individuals guilty of human rights abuses.

The U.S. imposed sanctions of its own, tightening restrictions on exports to Russia of national security-sensitive items.

This week Britain promised more — though unspecified — responses. Jeremy Fleming, who heads the U.K.‘s GCHQ electronic spy agency, said Thursday that Britain would use “the full range of tools from across our national security apparatus.”

Much of that action consists of strengthening British cyber-defenses against Russian hackers. Britain could also take offensive action of its own against Russian websites, though officials stress the U.K. sticks within the law — and British officials may not want to escalate international cyber-conflict.

Some doubt U.K. actions will hurt Moscow much. A cartoon in Friday’s Daily Telegraph newspaper showed a kitten-heel shoe in May’s favorite leopardskin print bouncing harmlessly off a giant Russian bear ridden by Putin.

Telegraph columnist Fraser Nelson said the Salisbury nerve-agent attack had been a triumph for the Kremlin, “showing the world that it can strike anywhere, with relative impunity.”

Conservative lawmaker Tom Tugendhat, who chairs the British Parliament’s Foreign Affairs Committee, said there is one sure way to halt the meddling — go for the money.

London is a magnet for wealthy Russians, and critics of Putin say Britain should do more to stop the president’s wealthy backers from enjoying their money and property in the U.K.

Shortly before Skripal was poisoned, Britain introduced powers to seize money and property whose origins are suspicious. But Tugendhat’s committee reported in May that those powers had barely been used, and accused the British government of turning a blind eye to dirty Russian money.

Tugendhat said Friday he has been assured the government “is now taking it extremely seriously.”

“We’ve got to make sure that people who have struck a deal with Putin over the last 10, 15 years — where the deal went, Putin gets the power and you get the money — realize the deal doesn’t work anymore because the money is worthless,” he said.

“You can’t go to Paris, London and New York; you can’t send your kids to the best schools; you can’t dine out in the best restaurants. All you are is a prisoner in a golden cage.”