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."