A female suspect named Gao Yu was detained for leaking "state secrets" to foreign contacts, said Beijing police on Thursday. Gao, 70, a Beijing resident and a former journalist, was suspected of illegally obtaining a highly confidential document of the Chinese central government and sending it to an overseas website in June last year, which later became widely circulated on foreign websites.

This is the third case reported this week on overseas espionage, which highlights the grave challenge to national security. It's high time the related authorities tightened regulations on classified documents and raised people's awareness of protecting state secrets.

Early this week, the existence of an Internet-based espionage ring in Guangdong province has once again underscored the need to safeguard military secrets in the Internet era. The spy network came to light when provincial security agency discovered that a foreign intelligence agency was using the Internet to "recruit" Chinese nationals to steal China's military secrets.

A suspect surnamed Li has been sentenced to 10 years in prison for leaking to a foreign spy 13 highly classified documents and 10 classified military secrets, which he obtained by subscribing to some internally circulated military publications and monitoring important military bases in Guangdong. Li has passed on a large number of photographs of these bases and other crucial military facilities to the foreign intelligence agency.

According to information given by the provincial authorities, a foreign spy known as "Feige" recruited 12 Chinese nationals in the province and 40 others in other parts of the country to collect valuable information on China's military. Reports suggest that "Feige" targeted youths interested in military matters and unsuspecting students through some Internet chatrooms, communities, campus forums and job-seeking websites.

Security officials have also detected about 30 cases of Chinese students being "recruited" or targeted through the Internet by another foreign spy called "Li Hua" since 2012. National security agencies have confirmed the findings on the basis of sound evidence, saying most of the students were "approached" on online chatrooms or job-seeking websites.

China is not the only country to be targeted by "Internet spies". The United States, known for its highly developed intelligence infrastructure and for spying on other countries, has also fallen victim to Internet spying. The personal information on 100,000 US Navy and Marine officers and soldiers was leaked in 2006 creating shockwaves in the American intelligence set-up. The leakage turned out to be the result of a casual disclosure of their personal information, including their names, social security numbers, service units and some work photographs on the US' Marine safety website a few months earlier.

US military experts had then warned that the personal data contained some classified information. For instance, they said the US' military deployment plans could be traced by analyzing the introductions to the personnel's service units.

The leakage came only two weeks after the names, dates of birth and social security numbers of 28,000 US Marines and their relatives were published by a civilian website, accessible to all Internet users.

The series of leakages prove that even the country with the most sound and foolproof intelligence network can fall victim to spying or casual acts of commission if it doesn't take necessary and appropriate safeguard measures.

The development of the Internet in China has been rapid over the past decade; in fact, the country now has the highest number of Internet users in the world. But it is still far from being a cyber power, both in terms of software development and safeguarding information. A large number of Chinese netizens are yet to develop the necessary risk-alert awareness even though they make full use of the limitless cyberspace.

In an interview with Beijing Television in 2013, Zhang Zhaozhong, a Chinese military expert, had said that the US could steal some military secrets from China by making some Chinese netizens unconsciously play the role of spies via the Internet.

The success of a military strategy during a war depends, to a large extent, on how well it is kept a secret. So, China should spare no efforts in safeguarding its military intelligence, especially at a time when it is deeply engaged in protecting its sovereignty and territorial integrity.

In a move to meet the new secrecy challenges facing China and make its military more secure, the Central Military Commission of the Communist Party of China has issued a document saying military secrets should be better protected. To achieve this, the authorities should take measures to plug all the possible loopholes in Internet management and brace themselves for an increasingly fierce Internet warfare, which in most cases is carried out surreptitiously.

Every Chinese netizen can help the country in this warfare by refraining from posting sensitive information on the Internet, consciously or unconsciously. While surfing the Internet, every Chinese netizen should guard against being used as a spying tool by some foreign intelligence agency or the other.

And since almost all magazines and periodicals have online editions, the authorities should formulate a set of strict publication and circulation rules and methods for military periodicals to prevent foreign spies from easily accessing them and stealing China's secrets.

The author is a senior writer with China Daily. wuyixue@chinadaily.com.cn.