When John Kerry took to Twitter on his first day as US secretary of state, he joined an army of diplomats using social media to reach out and connect directly with people around the world.

"Exhilarating to walk into @StateDept today and get to work with remarkable team. Dad on mind! -JK," Kerry wrote in his first personal tweet.

In less than 140 characters, the new US top diplomat instantly signaled he intended to carry on and deepen a commitment to using social media begun under his predecessor Hillary Clinton.

Clinton did not tweet, but she propelled the State Department towards what she called 21st Century Statecraft, and social media engagement has taken off.

There are now more than 300 Twitter accounts with some three million followers, over 400 Facebook pages with close to 20 million fans, and 185 YouTube channels as well as Flickr, Google+ and Instagram links run by the State Department, its embassies, staff and diplomats.

Most of the embassy Facebook pages are written both in English and the local language, and the official Twitter accounts are in 11 languages including Arabic, Chinese, Farsi, Hindi, Russian and Turkish.

"We want to participate in the conversations that are taking place around the world every day," said Deputy Assistant Secretary Victoria Esser, in charge of managing digital strategy within the public affairs department.

"The secretary is really committed to using these tools to help us advance our diplomatic goals... It's going to continue to make our diplomats more effective in today's world," she told AFP.

The State Department on Friday will host its first ever tweet-up, asking followers on its @StateDept account, Facebook and Google+ to join it to cover the annual International Women of Courage award.

Absent any diplomatic ties with Iran, there's even a "virtual embassy of Tehran" (http://iran.usembassy.gov/) set up in late 2011 and managed from Washington carrying information about visas and studying in the United States.

But while US diplomatic staff are excited about expanding their reach beyond the traditional embassy walls, there's a recognition of the inherent problems associated with such freedom.

As Kerry said during a trip to Rome diplomats are now working in "an age where it isn't a letter that comes from the cardinal to the king in some place; it's instantaneous."

Last year, the Kremlin got involved in a heated Twitter row with US envoy Michael McFaul, the US mission in Cairo was under fire for a statement released about an anti-Islam video and Beijing has been infuriated by a US embassy Twitter feed monitoring pollution levels.

"It's a good way to communicate, and it's a new way to communicate, and it's omnipresent in everyone's lives. So my feeling is that we should explore this and use it where ever we can," said US ambassador to Italy, David Thorne.

But he cautioned: "I think it's a challenge to the State Department to manage the message this way, and have a way of interacting with the public that doesn't get misconstrued. We're constantly trying to figure out how to do that."

During the 2012 White House race, Thorne -- who honed his social media skills running Kerry's 2004 online presidential campaign -- wrote a weekly blog for La Stampa daily and on election night 2,000 people packed into a room to follow the results electronically.

"In this business, you never get to talk to as many people as you'd like. Twitter provides a way for me to connect directly with those I might otherwise miss," said US ambassador to Thailand, Kristie Kenney.

She has over 38,000 followers on her Twitter account, and the embassy's Facebook page has some 124,000 likes. Kenney writes all her own Tweets and says "common sense is my guide."

"Twitter and other social media tools can be a great complement to diplomacy, but this profession still involves a good deal of discretion."

Meanwhile, the department is also actively engaged in ensuring that people around the world can enjoy what Clinton called "the freedom to connect."

Some $100 million has been earmarked by Congress since 2008 for training and developing technology to ensure "the openness of the Internet as a platform for citizens around the world, particularly in repressive countries," said Katharine Kendrick, Internet freedom team member with the department's Bureau Of Democracy, Human Rights and Labor.

"The US was the first government to put Internet freedom as a policy issue on the map at such a high level as the secretary did. And since then we've been actively trying to recruit others to this space."

One grant helped a company develop a panic button for mobile phones which when activated wipes your contacts and tells your friends you're in trouble.

"If you're an activist in many countries in the Middle East the primary threat is not that your blog is censored, it's that you as an individual are tracked," said Kendrick.

"The Internet is not a kind of exceptionalist space where government commitments fall by the wayside. We see it as an extension of our existing human rights," she added.