Colombia, traditionally one of Washington’s strongest allies in Latin America, has just signed a “strategic partnership” with Communist China. The nation’s guerrilla-turned-president, Gustavo Petro, signed the deal at Beijing this week. He has complained that his nation’s foreign policy was “subordinate” to Washington.

On the commercial front, Colombia, a middle-income nation of 52 million people, offers a juicy market to Chinese exporters. On the strategic front, Colombia is South America’s only nation with Atlantic and Pacific coasts. The new deal with China will add new energy to a decade-old proposal to build a “dry canal” between the Pacific and the Caribbean. 

Billed by Chinese investors as an alternative to the 109-year-old, American-built Panama Canal, Colombia’s “dry canal” would be a Chinese-built railroad running 136 miles through thick jungle between two new container ports, both built by Chinese companies.

While this land bridge may be far in the future, today’s mood music is favorable. In 2026, China Harbor Engineering Company and Xi’an Metro are to complete a $4 billion project: the first two subway lines for the Bogotá Metro. For the capital’s suburbs, China Civil Engineering Construction Corporation is building a 17-station light rail network.

For Medellín, Colombia’s second largest city, China Harbor is to complete next year a $650 million highway winding 158 miles down from the Andes to the Gulf of Urabá, coincidentally the proposed terminus region for the railroad from the Pacific. Also at Medellín, China Railway Road Corporation has won a $3.5 billion public-private contract to build a metro across the city. Another Chinese company, Capital Airport Holding Company, now manages Medellín’s two airports and five other airports in the Antioquia department.

A railroad linking the Pacific and the Caribbean would stand as “a symbol of China’s economic incursions into what the US once considered its backyard,” Britain’s Guardian wrote. Or, as a Foreign Policy headline read recently: “As China Eyes Colombia, the United States Is AWOL; The country is a test case for Beijing’s encroachment in Latin America.”

China’s move on Colombia is part of a larger drive to cultivate ties with countries on South America’s Pacific Coast. China now has free trade agreements with Chile, Ecuador, and Peru. In Peru, China’s Cosco is building a mega-port. In Chile, Chinese companies have invested in lithium mining, electricity generation, and construction of a high speed railway from the Pacific to Santiago.

Colombia’s alliance with America dates back to the Korean War. Colombia was the only Latin American country to send troops to fight alongside American soldiers. At that time, the 5,100 Colombia soldiers of Batallón Colombia fought Chinese communist soldiers. Since then, Colombia has condemned North Korean nuclear tests, sent troops to Afghanistan, and was the only Latin American nation to support the war in Iraq. As recently as a decade ago, President Santos wanted Colombia to move toward joining NATO.

However, over the last decade two factors intervened: the explosive growth of Chinese trade and investment in Latin America, and last year’s election of President Petro, Colombia’s first leftist president. Mr. Petro got his political start battling the state for almost two decades with the M-19 armed guerrilla movement. Later, he was elected mayor of Bogotá.

On the economic front, during the 2000s, trade between China and Latin America increased by 1,200 percent, to $130 billion from $10 billion. In most of South America, China has displaced America as the top trading partner. Catching up, Colombia now lists China as its second-largest trading partner, after the United States. 

In 2002, Colombia’s trade with China totaled $543 million. By 2022, bilateral trade hit $22.6 billion — a 42-fold increase. However, Colombia has South America’s largest trade deficit with China — $8 billion.

Oil accounts for almost half of Colombia’s exports. Over the last decade, three Chinese oil companies have invested in producing oil in Colombia: Sinopec, Sinochem, and China National Offshore Oil Corporation. Over the last decade, membership in the Colombian Chinese Chamber of Investment and Commerce has increased 5-fold, to 150 companies. 

“As of 2022, there were at least 100 PRC-based companies operating in Colombia, including 38 active investment projects totaling $2.04 billion,” a U.S. Army War College Latin America research professor, Evan Ellis, wrote recently in a paper for Washington’s Center for Strategic and International Studies.

Mr. Ellis predicted: “Under the Petro government, all dimensions of Colombia’s relationship with the PRC, from political and security affairs to economic ones, are poised to expand and shift in ways that may cause unease in Washington.”

Although every Colombian president has visited Beijing since 1996, this week’s three-day visit, complete with an honor guard at the Great Hall of the People, was special. Doing advance work was Colombia’s new ambassador to China, Sergio Cabrera. The son of Colombian communists, Mr. Cabrera grew up in China during the Cultural Revolution. After attending Beijing University, he returned to Colombia to fight in the ranks of the People’s Liberation Army, a Maoist guerrilla group. A fluent Chinese speaker, Mr. Cabrera later returned to China to start his filmmaking career.

A warm welcome was given by President Xi, who had visited Colombia in 2009 when he was China’s vice president. Mr. Xi said: “We have become good friends and partners for win-win co-operation and common development.” Eying Colombia’s $350 billion economy, he invited Mr. Petro to join his global infrastructure project, the Belt and Road Initiative. 

Mr. Petro said he “highly values the Belt and Road Initiative,” according to a China Daily report, and adds that “Colombia wants to align its geographical advantages and development strategy with the BRI, strengthen cooperation with China in infrastructure, clean energy, and other fields.”

Now, Chinese investors and construction companies are studying Colombia’s long-neglected Pacific coast. Chinese companies would like to upgrade the oil exporting port of Temuco and build a natural gas regasification terminal at Buenaventura. Investors have studied creating new ports in Tribugá and the bay of Málaga. 

Holding investment back has been gang violence and a system of collective land rights by the region’s overwhelmingly Afro-Colombian inhabitants. Here China may find an ally in Colombia’s new vice president, Francia Márquez. A native of Cauca, a Pacific Coast department, Ms. Márquez also has a new portfolio ­­­­­­— Minister of Equality and Equity. Chinese investment could be a key to bringing jobs and development to her coastal constituents.

Watching China’s advances from Florida, where he commanded America’s Southern Command, Admiral Craig Faller of the U.S. Navy told the Senate Armed Services Committee two years ago: “We are losing our positional advantage in this Hemisphere, and immediate action is needed to reverse this trend.” He concluded: “Investing in our neighborhood is an investment in national security.”