Samantha Vinograd is a CNN national security analyst. She is a senior adviser at the University of Delaware's Biden Institute, which is not affiliated with the Biden campaign. Vinograd served on President Barack Obama's National Security Council from 2009 to 2013 and at the Treasury Department under President George W. Bush. Follow her @sam_vinograd . The views expressed in this commentary are her own. View more opinion articles on CNN.

(CNN) President Donald Trump isn't the only one who likes spending time at Mar-a-Lago. It's a goldmine for foreign intelligence because of the relatively easy access to the President — and many of his communications — that it provides.

So, this week, while he settles into his self-proclaimed "Winter White House," he may have some unexpected guests. Rudy Giuliani was seen at Mar-a-Lago this weekend, and the FBI and the federal investigation into Giuliani reportedly includes a counterintelligence probe. Just by talking to Giuliani, whether it be while Giuliani is on his unsecured phone or in person, Trump is increasing his own counterintelligence risks.

And there are myriad security risks at Mar-a-Lago. The Secret Service has acknowledged that they don't determine who is invited or welcome there — and, just last week, the second Chinese national this year was arrested for trespassing on the property. Neither Chinese national has been charged with spying at this point.

While Trump spends his vacation indulging in his favorite activities, he's expected to focus on his impeachment and stoking conspiracy theories. If he continues indulging his bad habit of speaking with people like Giuliani on his personal lawyer's unsecured mobile phone , Trump may be having conference calls with foreign intelligence services — like China — without even planning it.

We should expect the usual torrent of Twitter lies to abound during the President's two-week hiatus from Washington, including his jaded (and debunked) claims about impeachment hoaxes, perfect calls, witch hunts, and Obama spying on his campaign.

When Trump does focus on work over the holiday break, he should focus on one of the key threats facing the United States in 2020 — the intelligence danger from China. It hits close to home and has already likely impacted Mar-a-Lago itself. China is upping its spying game, and instead of making their job easier by cloaking himself in insecurities, Trump should focus on what our home team needs to mitigate this growing threat.

A tale as old as time: the stakes

There's nothing new about spying. We do it, China does it, and about every other country does too. Our own intelligence community assesses that China, along with Russia, poses the greatest state intelligence threat to the United States and that China remains the "most active strategic competitor responsible for cyber espionage against the US government."

JUST WATCHED Schiff warns of cybersecurity threat from ZTE Replay More Videos ... MUST WATCH Schiff warns of cybersecurity threat from ZTE 00:43

FBI Director Christopher Wray said unequivocally this summer that, "There is no country that poses a more severe counterintelligence threat to this country right now than China," adding that China is trying to "steal their way up the economic ladder at our expense."

Wray stated , "No country poses a broader, more severe intelligence-collection threat than China ... They're doing it through Chinese intelligence services, through state-owned enterprises, through ostensibly private companies, through graduate students and researchers, through a variety of actors all working on behalf of China."

High-value targets

Looking back on 2019 alone, it's clear that the Chinese have been going after some high-value targets. Three former US intelligence officers have been sentenced for espionage-related charges involving China (there may be more as many espionage cases don't go public), which means that China was able to identify and co-opt at least three Americans who had at least some degree of counterintelligence training because of their professional backgrounds.

JUST WATCHED DOJ charges 2 Chinese nationals with hacking Replay More Videos ... MUST WATCH DOJ charges 2 Chinese nationals with hacking 01:26

By focusing on former intelligence officials, China can get access to sensitive information including the names of US intelligence assets overseas. But China's targeting other US government officials, too. In April, a former State Department employee pleaded guilty to "conspiracy to defraud the United States, lying to law enforcement and background investigators, and hiding her extensive contacts with, and gifts from, agents of the People's Republic of China, in exchange for providing them with internal documents from the U.S. State Department."

The 2015 hack of a US government personnel database — which resulted in the theft of more than 20 million files — may have provided China with data it can use to identify former government officials. US officials linked that hack to China (China denies involvement).

Our own law enforcement and intelligence community are working hard on counterintelligence investigations but it's clear that China is having success targeting former government officials.

'Tourism' is trending, and so is trespassing

Accessing sites used by the US military — or President for that matter — is another high-value target for foreign intelligence services. Just seeing where and how the US military is set up, trains, and how security works at military bases can provide valuable intelligence to foreign governments.

That's why when Chinese Embassy employees reportedly drove through the outer perimeter of a US navy base that headquarters Seal Team 6, and ignored a guard's order to turn around," an explanation that they were "sightseeing" seemed paper thin. According to the New York Times, at least one of the Chinese nationals involved was an intelligence officer under diplomatic cover.

JUST WATCHED Trump and Giuliani calls spark spying fears Replay More Videos ... MUST WATCH Trump and Giuliani calls spark spying fears 03:04

But it's not just "diplomats" who are visiting sensitive sites. Mar-a-Lago, where Trump is currently vacationing, has had its fair share of uninvited guests. Yujing Zhang was arrested for trespassing at Mar-a-Lago (while carrying four cellphones, a laptop, an external hard drive and a thumb drive), and last week Lu Jing was arrested for trespassing. She was told to leave Mar-e-Lago by security and returned and snapped pictures.

Human intrusions aren't the only ones we have to worry about. Chinese cyberattacks against key US government agencies, sites and individuals are a primary concern, including attacks against US Navy personnel and its contractors.

Uneven playing field

While China's intelligence agencies employ many tactics adopted by other services around the world, including our own, they're asymmetric advantages are becoming increasingly clear. The US intelligence community assesses that "China's intelligence services will exploit the openness of American society, especially academia and the scientific community, using a variety of means," and Beijing is leaning on expatriates, including Chinese students studying in the US, to steal information.

There are about 350,000 Chinese students studying in the US each year — and China is reportedly leaning on several of them — as well as Chinese businesspeople and scientists in the US. Even just by tapping into a handful of these Chinese expatriates, China has access to an impactful network of potential recruits for covert influence and other operations.

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While tapping into this network, China's also been relying on another asymmetric advantage — persistent cyber espionage. China can spy on US companies — and steal intellectual property, for example — without having to put any of its human agents at any physical risk. While we wait to see the details of the "Phase One" US-China trade deal, any credible commitments by China to cease this behavior will matter to US businesses and to our intelligence community.

Heading into 2020, we should expect China to continue its multi-pronged espionage efforts against the United States, particularly as we face a Presidential election. With a mix of traditional and 21st-century tradecraft, China will keep upping its spy games. Members of the law enforcement and intelligence communities are on record about the threat. While President Trump walks a trade deal tightrope with Xi Jinping, he should focus on getting China to back away from its asymmetric tactics by laying out real repercussions if they don't.