In the 12 days since Donald Trump took the oath of office, a steady stream of social media posts have called for the new president's assassination.

The posts are pretty basic and many are jokes or sarcastic or hyperbolic — but there are a lot of them. In a Dataminr search of Twitter posts since Inauguration Day containing the phrase "assassinate Trump" more than 12,000 tweets came up.

The U.S. Secret Service, however, or even Twitter and Facebook themselves, doesn't seem to be jumping onto many of these posts. When we asked several users about their recent "assassinate Trump" posts, all of them said they hadn't been contacted by anyone about their post and they all remain up.

But there have been reports of agents knocking on the doors of social media users. A Kentucky woman who tweeted, "If someone was cruel enough to assassinate MLK, maybe someone will be kind enough to assassinate Trump," is currently being investigated by the Secret Service, according to the Associated Press.

An Ohio man tweeted several messages about killing Trump on election night, according to NBC News. The Secret Service questioned him the next day and he was charged with making threats to the then president-elect.

"It’s the people who have a true and genuine intent to do harm that the Secret Service is worried about."

Former U.S. Secret Service special agent Tim Franklin, who is now a criminology and criminal justice professor of counterterrorism and cybercrimes at Arizona State University, said in a phone call Tuesday that "it’s the people who have a true and genuine intent to do harm that the Secret Service is worried about."

That's why one-off posts and people with no record of threatening messages tend to get passed over. He said the Secret Service is looking out for trends and consistent behavior, like the person who repeats their intent to kill the president over time. If someone has made threats in the past they are more likely to get investigated when they post another "Kill Trump" post.

"They're not going to to beat down the door of everybody who makes a negative Twitter comment," Franklin said, which may be a relief to anyone who tweeted an off-hand and not entirely serious death wish for the new president.

But for users who use certain language and specific details about the president, his location and how the assassination will happen, the Secret Service will likely take notice.

The U.S. Secret Service could not be reached for official comment about how they handle social media posts threatening to assassinate the sitting president.

On the platform side, Facebook and Twitter have policies in place to take down threatening posts. As Twitter said in an email statement, "The Twitter Rules prohibit threats of violence, and we will suspend accounts violating that policy." Facebook similarly said under their "credible threats policy" they remove posts showing intent to kill the president.

Yet thousands of posts that use the words "kill" and "assassinate" remain up — most of them targeting the president no less. The platforms can't seem to keep up with the influx of death threats and don't seem to be upholding their own policies as strictly as they would like.

Back when Trump was a presidential candidate, the Secret Service was full-on monitoring and investigating threats against him and Hillary Clinton. Now that Trump is president, his office is even more protected; threats against him and his vice president Mike Pence can result in fines or imprisonment for up to five years.

Franklin, the former Secret Service agent, said because Trump heavily uses social media to talk about controversial executive actions and ideas, he is being targeted on Twitter more than Barack Obama or George W. Bush were during their presidencies, at least in these first days. But that's not to say Obama and Bush didn't get their fair share of online hate.

President Trump surround by U.S. Secret Service agents during his inaugural parade. Image: Official DHS photo/Barry Bahler

Franklin says for law enforcement it's not about the person or politics of the president, but about protecting the office. "We focus on the protection aspect and let others worry about politics," he said.

Nevertheless, as Franklin notes, "It’s an American right to be able to express those opinions." But maybe slow down on those violent rallying cries, and certainly don't let your rhetoric cross over into talk about inflicting bodily harm, killing or even kidnapping — there's a line, and if you cross it, be ready for a knock at your door.