As the political crisis in Venezuela continues to mount, tens of thousands of Venezuelans took to the streets Tuesday in dueling pro-government and pro-opposition protests. Opposition leader Juan Guaidó addressed his supporters and announced a deadline for allowing aid shipments to enter the country.

Juan Guaidó: “Today we announce that February 23rd is the day for humanitarian aid to enter Venezuela. We stand by all sectors—delivery drivers, nurses, medics—to get ourselves organized.”

Military officers, who in large part have remained loyal to President Nicolás Maduro, have been blocking access to supplies at the Venezuela-Colombia border. Critics have blasted the U.S. for using aid as a political tool to undermine Maduro’s presidency while garnering support for Guaidó. The Red Cross and the U.N warned the U.S. to not send aid to Venezuela without the approval of the sitting president. The U.N. said, “Humanitarian action needs to be independent of political, military or other objectives.” On Monday, Guaidó tweeted a photo of himself surrounded by pill bottles, saying that some aid in the form of nutritional supplements made it into Venezuela, although it’s unclear where they came from.