When we talk about spying, assassination, covert secret service activities, we love to reminisce about the time of heightened tension between the world's two superpowers back in the time of the Cold War. The ideological conflict between the US and the Soviet Union brought about spine-chilling novels, movies, and so on, many of which are based on true stories.

In the post-Cold War era, the nature of espionage altered in the new political landscape due to the revolution brought by the internet and other sophisticated technological equipment. Spies of the present operate in a completely new way from that of their predecessors. But these stories are also worth knowing.

Here we collected five tales of espionage that can compete with the best of the best.

China's theft of American nuclear secrets

In 1999, a storm brewed over Washington over a devastating report by the Congress revealing that Beijing had been stealing America's nuclear secrets for almost 20 years. The Cox Report, a 700-page catalogue detailing all about the espionage, exposed that China was becoming on par with the expertise of the US.

The report claimed that Beijing made a jump in developing its nuclear programme. Until that point, China's nuclear weaponry – system, software, and designs – were a generation behind the US's capabilities.

China made some breakthroughs accelerated by the theft of American secrets from a National Lab in New Mexico. It is assumed by the intelligence community that the espionage was occurring from the mid-'80s. But it was not detected until 1995 when Americans analysing Chinese nuclear test results found striking similarities to their most cutting-edge warhead, the W-88.

The White House was told of the full extent of China's spying in the summer of 1997. By the next year, government investigators identified a suspect, an American scientist at the laboratory, where the W-88 miniature atomic bombs were built.

The case of double agent Robert Hanssen

Robert Hanssen was an FBI agent who spied on the US for 22 years on behalf of the Soviet Union until he was finally caught in 2001. He was a veteran counterintelligence agent who was charged with double-crossing the FBI by sending classified data to his Soviet handlers. 

In the same year, Hanssen was prosecuted on 21 counts of spying against the US, although he avoided the death penalty in a plea that involved a life sentence without the option of parole.

Based on the amount, significance, and consequence of the information he gave away to the Russian counterparts, many intelligence specialists say that the case of Hanssen was the worst gaffe in FBI history. He was of great value as he had inside knowledge of the bureau's missions and spies, which enabled Russians to keep track from within the FBI.

General Dmitri Polyakov, a prized infiltrator of FBI working in the Soviet army and later executed after being apprehended, was compromised by the direct help of Hanssen.

The spy who deciphered his own murder

Alexander Litvinenko, a former spy of Federal Security Service (successor of infamous KGB), was murdered in November 2006. His killing spurred controversy and worsened relations between London and Moscow. Working many years for FSB, he escaped to London in 2000 after falling out over corruption within FSB. The UK granted him asylum.

Later he became a critic of Putin's Russia and wrote a book revealing classified information about his time performing for FSB. He was poisoned with Polonium-210 in a hotel in London on 1 November and died three weeks later. After being initially sick, he was admitted to a hospital but continued to help in the poisoning investigation process. 

He cracked the substance used to poison him, tracing it back to his two ex-coworkers who he met days back over a cup of tea at the Millennial Hotel. A public inquiry by the British Government found Putin's involvement in giving nod to assassinate him.

A heavy blow to CIA networks

A communications network used by the CIA to connect with its informants was compromised between 2010 and 2012, which resulted in the executions of dozens of US spies by the Chinese government. In the period that continued for two years, Chinese officials precisely located spies working for the CIA in Chinese territory. Spies detained by the Chinese intelligence were imprisoned or killed before they were able to determine what was happening.

The newly devised internet-based system was initially placed in China under the belief that the system was invincible and Beijing based intelligence community could not breach it.

This programme was assumed to be safe, encrypted, untraceable, and was specifically designed for the newly joined spies as a safety check for double-crossing the agency. But the failure was appalling, leading to the assassinations of at least 30 officials. Many consider this one of the biggest failures of the CIA.

The strange assassination of Kim Jong-Nam

On the morning of 13 February, 2017, at Kuala Lumpur's busy international airport, Kim Jong-Nam the half-brother of North Korean supreme leader Kim Jong-Un was killed in a bizarre fashion. While he was going to check in for his trip to Macau, a woman came at him and rubbed an oily material on his face, before vanishing quickly into the crowd. 

A few seconds later, another lady approached him and rubbed his face with her hands. She also left quickly after making an apology. Less than half an hour later, Kim was dead.

One of the women involved in the assassination said that she was fooled into taking part in the killing. She was recruited to make some prank videos in the airport terminal and paid around $100 each time. Her last prank's target was Kim Jong Nam, the half-brother of Kim Jong Un. Instead of harmless baby oil, she was unwittingly given a nerve agent to scrub over Kim's face, killing him as a result.