President Trump sharply intensified his threats against Iran on Wednesday, suggesting that if it did not agree to a set of demands the administration had made of the country’s leaders, he could soon mount an attack “with speed and violence.”

Mr. Trump’s threat of a second direct attack on Iran by U.S. forces in eight months came as the aircraft carrier Abraham Lincoln, along with other naval ships, bombers and fighter jets, took up positions in the region in striking distance of the country. Mr. Trump explicitly compared the buildup to the forces he amassed near Venezuela late last year, just ahead of the operation that seized Nicolás Maduro and his wife in the middle of the night early in January.

Mr. Trump gave no specifics about the deal he was demanding, saying only that a “massive Armada” was heading toward Iran and that the country should make a deal. But U.S. and European officials say that in talks, they have put three demands in front of the Iranians: a permanent end to all enrichment of uranium, limits on the range and number of their ballistic missiles, and an end to all support for proxy groups in the Middle East, including Hamas, Hezbollah and the Houthis operating in Yemen.

Notably absent from those demands — and from Mr. Trump’s post on Truth Social on Wednesday morning — was any reference to protecting the protesters who took to the streets in Iran in December, convulsing the country and creating the latest crisis for its government. Mr. Trump had promised, in past social media posts, to come to their aid, but has barely mentioned them in recent weeks.