Venezuela and its president , Nicolás Maduro, have proved to be favorite targets of the Trump administration’s ire. At the outset of a summit on Central America in Miami last week — on the sidelines of which the administration announced its retrograde Cuba policy — President Donald Trump told Secretary of State Rex Tillerson to “collaborate with countries in the region to move discussions on Venezuela forward,” according to a White House statement. “The United States stands with the people of Venezuela during these sad and troubling times for their country.”

Miami, however, was where Tillerson’s personal diplomatic entreaties were to end. The day after the White House statement, Tillerson cancelled his attendance at the Organization of American States’ 47th General Assembly, which is convening in Cancun, Mexico, on Monday, with Venezuela high on the agenda. Instead of participating directly, Tillerson will remain in Washington to address rising tensions in the Persian Gulf.

The change of plans reflects the State Department’s priorities, but also spares Tillerson a direct confrontation with his complicated history in Venezuela.

The general assembly comes as Venezuela is plagued by staggering inflation, food shortages, decrepit medical infrastructure, and violent political unrest. Those dynamics are being compounded by another diplomatic crisis: In April, Maduro’s Foreign Minister Delcy Rodríguez announced that Venezuela will be withdrawing from the OAS after 65 years, viewing the hemisphere’s premier diplomatic venue as an arm of a campaign in pursuit of regime change.

Venezuela’s crises are all the more vexing because, even as people starve today, it was once the wealthiest country in Latin America — Venezuela boasts the world’s largest proven oil reserves.

Enter the former ExxonMobil executive Rex Tillerson. While Tillerson headed the oil giant, a position he stepped down from to join the Trump administration, ExxonMobil took a significant blow from Maduro’s predecessor, Hugo Chàvez. In 2007, Chàvez nationalized the oil company’s Venezuelan assets, valued at $10 billion. ExxonMobil again faced off with Maduro in 2015, over drilling in disputed waters off the coast of Guyana. In that case, Tillerson prevailed.

Despite Tillerson’s fraught history with Venezuela, the country initially seemed willing to play ball with the Trump administration. A Venezuelan state-owned oil company donated $500,000 to Trump’s inauguration and, in February, businessmen with ties to Trump met with members of the National Security Council, including top White House adviser Steve Bannon, to discuss lifting sanctions on Venezuela. Maduro, for his part, took a softer line on Trump than one might expect from an anti-imperialist firebrand. “He won’t be worse than Obama,” the Venezuelan leader said as Trump was coming to power, comparing the new American president to his predecessor, Barack Obama.

The outreach, however, soon turned sour. As the current wave of violent antigovernment protests against Maduro grew in recent months, Trump began to speak of intervention and new sanctions. In mid-May, he announced sanctions against eight members of Venezuela’s Supreme Court after it found members of the Venezuelan opposition party in contempt and removed them from power. Maduro described the sanctions as an attempted coup, condemning Trump and commanding him, “Get your pig hands out of here!”

Yet the hands-on work of international wrangling in Cancun to confront Venezuela’s interwoven crises won’t be carried out by Trump’s top diplomat. Instead, it will fall to Tillerson’s Deputy Secretary of State John Sullivan, a longtime Republican bureaucrat with little experience in diplomacy, let alone on Venezuela.