Sameer Bhalotra has gone from personally advising President Obama on cybersecurity issues to heading up a Silicon Valley startup that strives to protect social networks from the prying fingers of organized crime. And while his job change could be seen as a move to warmer weather and a lower stress environment, it also reflects a stark political reality: It’s companies, not the government, that have to bear the responsibility of protecting citizens from the bad guys of the Internet.

Just over a week ago, Bhalotra (pictured above) assumed the chief operating officer role at Impermium, a social Web security startup that was build by former Yahoo engineers. Based in Redwood City, Impermium analyzes data from a network of 300,000 sites in real-time to preemptively head off suspicious activity before it can harm social networks. Bhalotra came to the position after serving two years as a senior director for cybersecurity at the White House, where he directly advised the President. Prior to that, he was the lead staff member for cybersecurity on the Senate’s intelligence select committee.

Bhalotra says that despite the shift from public to private, his mission stays the same: protecting people. “Some people who think about the cybersecurity issue get very much focused on the hardware – network switches, Internet protocol – and that’s very, very important,” he told me in a phone interview. “My view was, what are we protecting, and who are we protecting? It’s people – it’s users of the Internet, and it’s the companies.”

The conclusion he drew in the White House is that the burden of protection falls on the American companies that operate websites. Congress has decided that the government is not going to take a dramatically increased role in defending the social Web from cyber attacks in the near term, he says, and individual users aren’t in a position to adequately defend themselves against organized criminals.

An Obama-endorsed cybersecurity bill designed to prevent large-scale attacks on critical infrastructure didn’t get past Senate earlier this month. While Senators voted 52 to 46 in favor of the bill, it didn’t get the two-thirds majority it needed to overcome a Republican filibuster – a voting tactic, once viewed as extreme, that the GOP has deployed as a matter of routine since Obama came to office.

On the social Web front, that means it will be left to the likes of Facebook, Twitter, Pinterest, and Tumblr, to protect their sites and their users. The social Web is the next cybersecurity battleground, Bhalotra says. While he was in the White House, he received a daily digest documenting the efforts of cyber criminals. It was obvious that social networks were increasingly becoming a target. “It was rampant,” says Bhalotra.

The US is not the only target, he says. Transnational companies, nonprofits, financial institutions, critical infrastructure, influential bloggers, and citizens are all suffering from cyber attacks. “The cyber threat situation is dire,” he says, and it’s not getting much better. “I think the situation is getting worse.”

In the White House, however, cybersecurity is getting more attention than ever before. Obama has taken concrete steps to advance the issue, including creating the position of White House Cybersecurity Coordinator, to whom Bhalotra was deputy, and signing the National Strategy for Trusted Identities in Cyberspace. In 2009, he gave the first ever speech by a US President solely on the topic of cybersecurity, and in an op-ed published in the Wall Street Journal in July, he said, “The cyber threat to our nation is one of the most serious economic and national security challenges we face.”

Now that he has left the White House, Bhalotra might be forgiven for seeking a less stressful job. And working for the American people, he certainly had plenty to worry about. “Absolutely, you stay up at night sometimes… You can’t sleep sometimes worrying about what happens to the country if a malicious attacker decided to do the unthinkable to the United States.” But he takes his new role at Impermium just as seriously, and given the current political climate, he probably has good grounds for doing so.

As he puts it: “I still worry as much as ever.”