An indictment announced in Washington says Russia's military intelligence agency, known as the GRU, targeted the hacking victims because they had publicly supported a ban on Russian athletes in global sports competitions and because they had condemned Russia's state-sponsored athlete doping program.
And some are hoping - after Brexit - to exploit Britain's absence from the European Union to weaken sanctions next time they have to be agreed.
A laptop belonging to one of the four was linked to Brazil, Switzerland and Malaysia. Malaysia is involved in the investigation into the shooting down of flight MH17 over Ukraine in 2014, which the Netherlands holds Russian Federation accountable for. The global organization was investigating the use of chemical weapons in Syria and the poisoning of former GRU officer Sergei Skripal and his daughter, Yulia, in Salisbury in March.
"Bringing the concrete findings of intelligence services into the public arena is an unusual step", Bijleveld said.
The four men travelled into Amsterdam using diplomatic passports, and were escorted by a member of the Russian embassy in the Netherlands. Between 2016 and 2018 they also exchanged emails and private messages with some 186 reporters "in an apparent attempt to amplify the exposure and effect of their message", the Justice Department said in a news release.
On April 11, they then hired a Citroen C3 and scouted the area around the OPCW - all the time being watched by Dutch intelligence.
He said: "This GRU operation was trying to collect information about the MH17 investigation".
Eichelsheim said the four agents were operating out of a Citroen auto parked outside the Marriott Hotel, which is next to the organisations headquarters on Johann de Wittlaan.
Authorities also released photos on Thursday showing the auto the group of men used with a wifi antenna and technical equipment in the trunk of a vehicle, thought to be used to hack the network. Officials said the men were expelled from the country following the alleged cyber attack.
The Dutch spy chief said the Russians had originally taken a taxi from a GRU base in Moscow to the airport, and some of their mobile phones were activated in Moscow near the agency's headquarters.
Eichelsheim said the four Russians were "clearly not here on holiday".
The news came as Britain, which helped in the Dutch investigation, and Australia said Moscow was to blame for a string of recent high-profile cyber attacks on civilian bodies around the world. Russian Federation has denied any involvement in the plane's destruction. According to tech security companies there is little sign that Russian hackers will try to repeat their campaign in the run up to the 2016 Presidential election, but a report like this is a handy way of reminding Russian intelligence that western spies are watching.
"Western spy mania is gathering pace", a Russian foreign ministry representative told AFP.
Britain has also blamed the GRU for the poisoning of Russian former double agent Sergei Skripal and his daughter Yulia with a military-grade nerve agent in the English city of Salisbury on March 4.
"State-sponsored hacking and disinformation campaigns pose serious threats to our security and to our open society, but the Department of Justice is defending against them", the attorney general, Jeff Sessions, said in a statement.
The 29 allies are discussing cybersecurity at talks in Brussels, with the U.S., Britain, Denmark and the Netherlands due to announce that they will provide offensive cyber-capabilities for use by North Atlantic Treaty Organisation.
The GRU hackers are part of a group known as Fancy Bear.
This, though, is something that Britain hopes to avoid, for the wider message that the government wants to send to allies is that the United Kingdom will continue to cooperate with its European partners in the fight against Russian aggression after the United Kingdom leaves the EU.
"We are going to actually make it clear that where Russian Federation acts, we are going to be exposing that action", Williamson said.
"We'll continue working with allies to isolate, make them understand they can not continue to conduct themselves in such a way".
"By embarking on a pattern of malicious cyber behavior, Russian Federation has shown a total disregard for the agreements it helped to negotiate", Australia's Prime Minister Scott Morrison said.