Venezuela’s top court opened a criminal investigation against six opposition lawmakers Tuesday following last week’s failed attempt to spark a military uprising against President Nicolás Maduro.

The lawmakers are suspected of “betraying the homeland” and “instigating an insurrection,” among other charges, the pro-government Supreme Court said. Those facing accusations include prominent figures in the Venezuelan opposition such as Henry Ramos Allup and Luis Germán Florido.

The court initially had said seven faced investigation, but later in the day lowered the number to six without explanation.

The action came one week after opposition leader Juan Guaidó urged soldiers to oust Maduro, who has taken steps to reassert his authority in the aftermath of the failed uprising.

Additionally, the government announced that it was taking control of three private airports. Interior Minister Nestor Reverol described it as a necessary measure to “guarantee efficiency” and crack down on illegal activity.

Venezuela’s opposition-controlled congress, meanwhile, met to discuss a proposal for the country’s return to a regional defense agreement that dates from the Cold War — a move that could provide political cover for greater international involvement in the nation’s crisis. The matter was referred to an assembly committee.

Years ago, Venezuela and other left-governed nations pulled out of the U.S.-led defense pact, the Inter-American Treaty of Reciprocal Assistance.

U.S. officials have repeatedly said they are considering military “options” in the Venezuelan crisis, in addition to diplomatic and economic pressure that has been intensifying for months against Maduro.

Military police prevented journalists from e