OAKLAND, Calif. -Ukrainians working at Western tech companies are banding together to help their besieged homeland, aiming to knock down disinformation websites, encourage Russians to turn against their government, and speed delivery of medical supplies.

They are seeking, through email campaigns and online petitions, to persuade firms such as internet security company Cloudflare Inc, Alphabet Inc’s Google and Amazon.com Inc to do more to counter Russia’s invasion of Ukraine.

“Companies should try to isolate Russia as much as possible, as soon as possible,” said Olexiy Oryeshko, a staff software engineer at Google and a Ukrainian American. “Sanctions are not enough.”

He was one of nine tech activists interviewed by Reuters who are of Ukrainian heritage or are Ukrainian immigrants and are responding to a call by Kyiv to form a volunteer “IT army.”

Many companies have severed Russian ties due to new government trade curbs, but the activists are demanding more.

They are appealing to cybersecurity companies in particular, asking them to drop Russian clients, especially publishers of what they say is disinformation. If that happens, the publishers would be more vulnerable to online attacks.

Igor Seletskiy, chief executive of Palo Alto-based software maker CloudLinux, has pleaded for Cloudflare to drop several Russian news websites.

“Given that even Switzerland took sides, I think it would be an important statement if Cloudflare would do the same,” he wrote in an email to top executives, which he shared with Reuters.

Cloudflare said it terminated some clients because of sanctions and has begun reviewing accounts flagged in Seletskiy’s email, adding that it was proceeding cautiously because cutting ties would jeopardize customer security.

Spurred on by bombs exploding outside his parents’ home last week and concerned for the safety of a few of his Ukrainian colleagues who had not recently checked in, Vlad Goloshuk has appealed to a swathe of companies to help pressure Russia.

More than a dozen, among them security and web hosting providers, said they would do what they can. Some have dropped Russian customers or were considering doing so, according to replies shown to Reuters by Goloshuk, CEO of BrightestMinds, a company that helps businesses generate sales leads.

Philipp Lypniakov, who works for Spanish delivery app Glovo and has supported efforts to take down Russian websites, said he hopes the “IT war” will protect Ukraine.

Disruptions will send “a message, starting from average citizens to the high officials that, ‘Hey, this is unacceptable,'” he said.

Ukraine’s deputy minister of digital transformation told Reuters Wednesday that the online forces now numbered more than 250,000 people, carrying out their own ideas. This “IT army” has already reached over 50 million in Russia, in part through 100,000 phone calls using an automated recording demanding Moscow’s retreat, said the official, Alexander Bornyakov.

Suspension of services urged

At Google, workers including hundreds of Ukrainian heritage have signed an internal letter addressed to CEO Sundar Pichai calling on the search giant to deliver more aid to Ukraine and modify its services such as Maps and advertising tools, according to a company software engineer who spoke on condition of anonymity.

Google declined to comment. In recent days, it has barred Russian state media from advertising and distribution tools and increased safety measures for users in Ukraine.

Activists also are looking at ways to disrupt the lives of Russian civilians, aiming to weaken support for the war within Russia.

An online petition organized by Stas Matviyenko, CEO of restaurant order-ahead company Allset in Los Angeles, has called on U.S. developers of entertainment, payment, dating and other apps to block access in Russia.

Big Tech’s financial and supply chain muscle could help, too.

Silicon Valley-based humanitarian aid group Nova Ukraine has urged Amazon to donate worker time along with space for bandages and other crucial supplies on its cargo planes and vehicles heading to neighboring countries such as Poland.

“They have the scale no one else has,” said Igor Markov, a director of Nova Ukraine and a tech research scientist.

Amazon declined to comment. This week it said it would donate up to $10 million to organizations providing support in Ukraine.

Organizing aid for Ukraine online has consumed Julia Nechaieva, a product director at Amazon’s live streaming unit Twitch.

“I have only opened my working computer three times since last Wednesday,” she said. “To let my manager know that I’ll be off and to use donation matching.”