Venezuelan President Nicolas Maduro has struck a defiant tone amid mounting international pressure on him to stand down. He has accused the United States of planning a coup in the South American country, and warned President Trump in an interview broadcast on Spanish television that he is, "making mistakes that are going to stain your hands with blood!"

Maduro said he "accepts ultimatums from nobody," as more individual European nations followed through with a threat to back opposition leader Juan Guaidó after Maduro neglected to call a new national election by a Sunday deadline. The Trump administration has also enthusiastically backed Guaidó, who declared himself the interim president of Venezuela on Jan. 23.

"The military option is on (U.S. President) Donald Trump's table," Maduro told Spanish TV channel La Sexta (The Sixth) in the interview aired Sunday evening. He accused the U.S. of "wanting to return to the 20th century of military coups, subordinate puppet governments and the looting of resources."

Get Breaking News Delivered to Your Inbox

Asked if his country could descend into civil war, Maduro said, "only if the North American empire attacks us -- we will have to defend ourselves."

"Stop! Stop! Donald Trump! You are making mistakes that are going to stain your hands with blood! And you are going to leave the presidency stained with blood. Stop!," the embattled president told his interviewer, adding that Venezuelans, "have the capacity of dialogue and understanding. Let's respect each other. Or is it that you are going to repeat a Vietnam in Latin America?"

Tightening the screws on Maduro

Washington recently imposed new sanctions on Venezuela, specifically targeting its lucrative oil exports in an effort to undermine Maduro's income and loosen his grip on power.

With the EU's Sunday deadline for Maduro to call elections having passed, a number of European nations officially declared themselves in the Guaidó camp on Monday.

Germany joined Britain, France, Sweden, Austria, Denmark, Portugal, Lithuania, Latvia and Spain -- a major blow given Spain's deep historic and economic ties with Venezuela -- in recognizing Guaidó on Monday as the legitimate leader of the Venezuelan people. He also has the support of most of South America.

Spanish Prime Minister Pedro Sanchez said Monday that his government was, "working for the return of full democracy in Venezuela: human rights, elections and no more political prisoners." He also touted efforts to get humanitarian aid into the economically ravaged nation.

As CBS News correspondent Elizabeth Palmer has reported from the streets of Caracas, Guaidó has sought to keep up the pressure internally on Maduro as he gains international backing. Guaidó routinely joins the massive demonstrations in the streets of the capital, including the biggest one to date over the weekend, where thousands of Venezuelans are demanding change from the top.

The focus, as Palmer has reported, has been on pressuring Maduro's military commanders to abandon him and give their allegiance to Guaidó. Over the weekend the first senior member of Venezuela's military publically switch his loyalty to the "interim" government of Guaidó. Air force general Yanez Rodriguez said he was backing Guaidó, and claimed that 90 percent of the armed forces have lost faith in Maduro.

But as Palmer reported over the weekeend, Maduro still has supporters, thousands of whom staged a counter-demonstration on Saturday in Caracas. A new poll suggests, however, that they're in the minority; after years of economic decay, corruption and violence, the poll showed 82 percent of Venezuelans want Maduro to quit.

Venezuelan President Nicolas Maduro surveys the crowd using binoculars as he addresses a gathering of supporters organized by his United Socialist Party of Venezuela (PSUV) to mark the 20th anniversary of the Bolivarian Revolution, in Caracas, Venezuela, Feb. 2, 2019. GETTY

A meeting of senior leaders from 14 Latin American nations and Canada, known as the Lima Group, set for Monday in Ottawa was to focus on the standoff in Venezuela. All the countries involved have called for new elections in Venezuela, and this week they will discuss ways to increase the pressure on Maduro.

Canadian Prime Minister Justin Trudeau's office said humanitarian aid for Venezuela -- routed through Guaidó -- would be discussed in Ottawa. Getting foreign aid into the country, or even agreeing to do so, would be not only a humanitarian gesture but a highly symbolic and, for Maduro, emotive, signal that the obstinate president is losing control of his borders.