National security adviser John Bolton held a legal pad in a White House press briefing Monday with the words "5,000 troops to Colombia" written on it.

Reporters noticed the scribbled note on Twitter, with the first line appearing to say "Afghanistan — welcome to talks." Economic adviser Larry Kudlow turned the notes away from reporters during the briefing.

The note appears to refer to the situation in Venezuela, Colombia's neighbor. The U.S. announced last week it considers Juan Guaidó, the opposition leader of the country's National Assembly, as the legitimate president. More than a dozen other countries followed suit, backing Guaidó over the government of President Nicolás Maduro.

A close-up view of national security adviser John Bolton's notes during a press briefing at the White House on Monday, Jan. 28, 2019. Reuters

Bolton's notes were spotted while he and other officials were announcing the imposition of sanctions against a state-owned Venezuelan oil company.

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The White House has not ruled out the use of military force if the situation in Venezuela deteriorates further. Asked for comment on Bolton's note, a White House spokesperson replied, "As the president has said, all options are on the table."

On Sunday, Bolton warned Maduro that violence against U.S. diplomatic personnel, Guaidó or the National Assembly would prompt a "significant response" from the U.S.

Colombia is a U.S. ally and shares a 1,300-mile border with Venezuela.