(CNN) The White House is not tamping down tensions after national security adviser John Bolton was seen Monday holding a yellow legal pad inscribed with the words "5000 troops to Colombia."

"As the President has said, all options are on the table," a White House spokesman said when asked for an explanation of the notes, which were seen during a briefing with reporters about new sanctions on Venezuela.

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President Donald Trump has refused to rule out military options in Venezuela as the administration ramps up pressure on the country's ruler, Nicolás Maduro.

A Defense Department official said on Monday that there are no plans to send any forces to South America nor are any discussions ongoing at the policy or operational levels.

There are a limited number of US troops currently in Colombia as part of the Plan/Paz Colombia mission but that number is in the hundreds, the official said.

When asked about Venezuela on Monday, acting Secretary of Defense Patrick Shanahan told reporters, "Here in the Department of Defense, we are very closely monitoring the situation."

Colombia's foreign minister reacted to Bolton's notes Monday evening, saying he was unaware of the thinking behind them.

"Colombia does not know the reasons behind these notes and it is unaware of the real extent of them," said Colombian Foreign Minister Carlos Holmes Trujillo in a statement. "Colombia will continue to carry conversations with the United States on several topics and cooperating with the U.S. in any bilateral topics."

In the US' strongest rebuke of Maduro so far, Bolton and Treasury Secretary Steve Mnuchin announced sanctions earlier Monday against Venezuela's state-sponsored oil company that would block about $7 billion in assets and prevent $11 billion in assets over the next year, Bolton said.

Maduro faces a challenge from self-appointed interim president Juan Guaido as the nation becomes increasingly unstable. The embattled Maduro alleged Sunday that the United States has facilitated a "coup" to undermine him, referencing reports that US Vice President Mike Pence had pledged America's full support to Guaido.

Venezuelan Defense Minister Vladimir Padrino said Monday that the military is "ready to die" for its homeland, after Venezuela's military attaché in Washington, Col. José Luis Silva, defected Saturday and publicly backed Guaido.

This story has been updated.