At a news conference on the border between Colombia and Venezuela, Toledo stood beside a vast warehouse filled with white plastic sacks of rice, beans and sugar labeled "from the American people". Kevin Whitaker, US ambassador to Colombia, speaks as humanitarian aid is packaged at a warehouse near the Tienditas International Bridge in Cucuta, Colombia, on Friday. Credit:Bloomberg He said three more warehouses would be opening up in the region shortly and that his countrymen could count on aid arriving "as soon as they open the border gates in the next few days". But the Venezuelan military has blocked the Tienditas International Bridge linking the two countries with two shipping containers and a tanker, which has become a symbol of Maduro's standoff with the United States and its European and South American allies. Despite growing international political support for the opposition, the Venezuelan military has not defected en masse, and it remains unclear where the US and the opposition go from here.

Colombian Civil Defence officers stand near a table of food from US humanitarian aid at the warehouse. Credit:Bloomberg Maduro, who enjoys the support of China and Russia, rebuffed calls to let the aid into the country on Friday, local time, in a dueling news conference in Caracas. "The reality is there is no help. It's a message of humiliation to the people. If they really wanted to help they should lift all the economic sanctions, the financial persecution, and cancel the economic ban that robs us of billions of dollars," Maduro said. Nicolas Maduro during a televised press conference in Caracas, during which he denounced the presence of trailers of humanitarian aid brought to the Colombian border. Credit:Bloomberg He insisted that Venezuela is not facing a crisis, though during the news conference, the power went out twice.

The Trump administration has meanwhile reiterated its implicit military threat against Maduro and warned him to leave US diplomats and Venezuelan opposition figures unharmed. On Friday, national security adviser John Bolton reaffirmed in a tweet that "all options are on the table". Despite the warning, US and Colombian officials have said they do not plan to use military force to get tens of millions of dollars of humanitarian aid into Venezuela. The possibility of such an operation loomed on Friday as Isaias Medina, an ex-Venezuelan diplomat who broke with Maduro in 2017, called on the Trump administration to consider the military option. "The main objective here is to bring humanitarian assistance – and if it must be done by military support, so be it," he said at a news conference at UN headquarters in New York. Colombian Civil Defence officers fill boxes with aid resources. Credit:Bloomberg

But US officials have conceded that their most realistic option is to persuade members of the Venezuelan military to defy Maduro's order to block the aid. Toledo on Friday appealed to the armed forces. "Members of the military, this aid is also for you. Here is food for your children, medicine for a people that's suffering. Here is help for children. Your job is not to condemn your people, it's to help them," he said. Guaido and his team have started speaking about a humanitarian corridor into the country, although with this border crossing blocked off, it was unclear how that would work. Loading Toledo said a previous border closure between the two countries had been called off when thousands of women protested, "dressed in white and with their arms raised".

The director of the Colombian emergency department, Eduardo Jose Gonzales Angulo, said the delivery of aid was a five-stage process but that the final two stages – moving the aid to the border and distributing it within the country – would be up to Guaido and his team. Anxieties over a US military intervention spiked last month after Bolton appeared at a news media briefing with a yellow notepad that read "5000 troops to Colombia". On Wednesday, Colombia's foreign minister, Carlos Holmes Trujillo, met with Bolton to discuss steps forward. In an interview, Trujillo downplayed Bolton's comments, saying there is "no plan of an immediate military" operation. However, he emphasised that there was no turning back from regime change in Venezuela. "There is no plan B. The only plan is the definite change in Venezuela," he said. "This is a process that is moving on. This is an irreversible process." Loading

When asked how US aid might make it into Venezuela, a spokesman for the US Agency for International Development said the United States was working with Guaido on a plan, but did not disclose any details. "Before providing aid, we require that adequate provisions be in place to ensure that those receiving U.S. assistance, our partners, or our staff will not be inadvertently put in harm's way," the spokesman said. The Washington Post