Venezuelan opposition leader Juan Guaido on Saturday said he has instructed his political envoy in Washington to immediately open relations with the US military, in an attempt to put more pressure on President Nicolás Maduro to resign.

Guiado said he had asked Carlos Vecchio, who the US recognizes as ambassador, to open “direct communications” toward possible military “coordination”.

The remarks, at the end of a rally, were Guaido's strongest public plea yet for greater US involvement in the country’s fast-escalating crisis. While Guaido has repeatedly echoed comments from the Trump administration that “all options” for removing Maduro are on the table, few in the US or Venezuelan opposition view military action as likely. Nor has the White House indicated it is seriously considering such a move.

But with tensions between the US and Maduro running high, the saber rattling is getting louder.

On Saturday, Venezuelan defense minister Vladimir Padrino condemned what he said was an illegal incursion by a US coast guard cutter in Venezuelan territorial waters. He provided no evidence but said Venezuelan vessels forced the ship to withdraw.

“I don’t know if other republics will accept actions like this in their jurisdiction, but we will not,” he said.

Col Amanda Azubuike, a US Southern Command spokeswoman, said a coast guard vessel was conducting a drug interdiction mission in the international waters of the Caribbean sea. She declined to provide further comment.

In past days, Padrino also denounced what he said were attempts by the US military to sow discord inside Venezuela’s barracks, inviting an angry response from Adm Craig Faller, head of Southern Command, who said he “stands ready” to assist Guaido.

“I look forward to discussing how we can support the future role of those [leaders of Venezuelan armed forces] who make the right decision, put the Venezuela people first and restore constitutional order,” Faller said.

As head of the National Assembly, Guaido launched a campaign in January to oust Maduro, gaining the support of the US and more than 50 nations.

He announced on Saturday a forthcoming meeting with US military officials and said new actions will seek to “achieve the necessary pressure” to put an end to the Bolivarian revolution launched 20 years ago by the late socialist president Hugo Chávez.

Guaido has said that as Venezuela’s rightful leader he reserves the right to invite foreign military actions in the way independence hero Simon Bolivar hired 5,000 British mercenaries to liberate South America from Spain. He says any such help should be considered “cooperation” instead of intervention, something he has accused Maduro of allowing in the form of military and intelligence support from Cuba and Russia.

In recent days, the government has sought to ramp up its own pressure on the opposition with the arrest of the No2 of the National Assembly, Edgar Zambrano. Several other anti-Maduro lawmakers sought refuge in embassies as the country’s top court announced investigations of Zambrano and nine other members of congress.

Noticeably diminished crowds at opposition protests reflect demoralization that has permeated Guaido’s supporters after he led a failed military uprising on 30 April. In previous months, thousands heeded his calls to protest. On Saturday, a modest crowd of several hundred gathered in Caracas.

“We live in dictatorship,” Guaido said, urging his supporters to press on. “We don’t have the option to stay at home waiting, but to keep demanding our rights in the streets.”

Guaido argues that Maduro illegitimately won a second term in rigged elections and has declared himself interim president of Venezuela. Maduro has maintained control of the military. He calls Guaido a “puppet” of the Trump administration and says the US is supporting a coup to oust him and exploit the country’s vast oil wealth.

“The US empire aims to end the Bolivarian Revolution,” Maduro tweeted early on Saturday, boasting of the country’s education and social security systems. “We show the world that we can do social justice.”

A once-wealthy oil nation, Venezuela has sunk into economic and social collapse marked by soaring inflation and a scarcity of basic goods that has sent an estimated 3.7 million of its citizens to emigrate.