President Donald Trump recognized Juan Guaido as the interim president of Venezuela minutes after the opposition leader declared himself the head of state, in the U.S.'s most provocative move yet against the leftist regime of Nicolas Maduro.

Guaido, 35, is the president of the Venezuela National Assembly, which Maduro doesn't recognize.

"In its role as the only legitimate branch of government duly elected by the Venezuelan people, the National Assembly invoked the country's constitution to declare Nicolas Maduro illegitimate, and the office of the presidency therefore vacant," Trump said in a statement. "The people of Venezuela have courageously spoken out against Maduro and his regime and demanded freedom and the rule of law."

Shortly before Trump's statement, Guaido said in a webcast from a protest in Caracas that he would assume the powers of the Venezuela presidency. He invoked a constitutional amendment that allows for the head of the legislature to lead a caretaker government until new elections can be held.

Read our Life in Caracas series here.

Since taking the helm of the legislature on Jan. 5, Guaido has aggressively pushed the military and the international community to recognize him as the rightful head of state.

"I swear to formally assume the powers of the national executive as interim president of Venezuela to achieve the end of the usurpation," Guaido said on stage in East Caracas before thousands of Venezuelans who rallied around him on Wednesday. The crowd cheered and sang Venezuela's national anthem after Guaido took the oath.

The U.S. has steadily expanded economic sanctions and denunciations of Maduro since Trump took office, all but urging that Venezuelans overturn their government. Venezuela's dollar bonds, which have gained 25 percent on average this year, rallied further on Wednesday as the opposition increased pressure on Maduro. While most of Venezuela's bonds are in default, investors believe regime change could usher in plans to fix the economy and restructure the debt.