"The armed forces will remain deployed and on alert along the borders... to avoid any violations of territorial integrity," said Defense Minister Vladimir Padrino, reading out a statement in a public appearance alongside top commanders.

"We reiterate unrestrictedly our obedience, subordination and loyalty" to President Nicolas Maduro, he added.

Maduro faces calls to quit as his country struggles with shortages of food and medicine.

The military high command has so far maintained its public backing for Maduro -- seen as key to keeping him in power.

Guaido, leader of the Venezuelan legislature, has declared himself acting president and is appealing to military leaders to switch allegiance to him.

He is backed by the United States and some 50 other countries.

The United States has sent food and medical aid for Venezuela but the military has so far refused to let it enter the country.

Guaido, 35, has offered military commanders an amnesty if they abandon Maduro.

On Tuesday he published a series of tweets calling by name on senior military leaders commanding border posts to abandon Maduro.

Trump has refused to rule out US military action in Venezuela. He raised the pressure on Monday, issuing a warning to the Venezuelan military.

He told them that if they continue to support Maduro, "you will find no safe harbor, no easy exit and no way out. You will lose everything."

Padrino rejected Trump's threat, branding the US president "arrogant."

Maduro's government says the aid is a smokescreen for an invasion.

If foreign powers try to help install a new government by force, they will have to do so "over our dead bodies," Padrino said.