The US-backed Guaido had set February 23 as his flashpoint date for a showdown with the government of President Nicolas Maduro over foreign humanitarian aid, which was being stockpiled in Colombia, Brazil and Curacao. Fearing that the US convoys could be an attempt to smuggle arms to the opposition, Maduro closed off the country's borders with its neighbors and suspended diplomatic relations with Colombia. Amid Washington-led calls for Venezuelan military officers to defect and for Maduro to resign, the army has mostly stayed loyal to the elected government and blocked the 'aid' cargo from entering Venezuela, despite sporadic clashes with opposition activists at the border. Following the failed delivery attempt, the US will send Vice President Mike Pence to Bogota, Colombia, on Monday to discuss a further course of action with Guaido on the fringe of the Lima Group meeting there. Washington, which seeks the overthrow of Maduro’s government, meanwhile also threatened to impose further economic sanctions, unless the aid reaches the Latin American country. Venezuelan authorities insist they would accept European aid or deliveries under the auspices of the UN, but would never allow US shipments to cross the border and go directly into the hands of the opposition, bypassing official channels.