WASHINGTON (Reuters) - The Venezuelan opposition’s envoy to the United States said he met Pentagon and State Department officials in Washington on Monday to discuss “all aspects of the Venezuelan crisis.”

Carlos Vecchio, opposition leader Juan Guaido’s ambassador to Washington, said in a message on Twitter that the talks held at the State Department had been “very positive” but offered no further details. “We continue to advance,” he said.

The talks were arranged at the request of Guaido, leader of the opposition-controlled National Assembly who invoked the constitution to assume an interim presidency in January, arguing that socialist President Nicolas Maduro’s 2018 re-election was illegitimate.

The United States and many European and Latin American countries have recognized Guaido as Venezuela’s rightful leader. But Maduro retains control of state functions and the support of the military’s top brass, as well as allies such as Russia, Cuba and China.

The purpose of Monday’s meeting was to discuss the U.S. Defense Department’s “past and future role related to humanitarian assistance and regional support,” a State Department official said ahead of the talks.

President Donald Trump and senior aides have not ruled out military action in the crisis-stricken South American country, repeatedly saying that “all options are on the table.”

But Washington has made clear it prefers to exert continued economic and diplomatic pressure to push Maduro out, and many experts have said the U.S. use of military force is unlikely.