DUBAI, United Arab Emirates — The United States will launch an effort on Monday to “guide” stranded ships from the Iran-gripped Strait of Hormuz, President Donald Trump said, giving few details about what could be a sweeping attempt to help hundreds of vessels and some 20,000 seafarers. Iran quickly denounced it as a ceasefire violation.

Trump said in a social media post on Sunday that “neutral and innocent” countries have been affected by the Iran war, and “we have told these Countries that we will guide their Ships safely out of these restricted Waterways, so that they can freely and ably get on with their business.”

“Project Freedom” would begin on Monday morning in the Middle East, Trump said, adding that his representatives are having discussions with Iran that could lead to something “very positive for all.”

U.S. Central Command said the initiative would involve guided-missile destroyers, more than 100 aircraft and 15,000 service members. The Pentagon did not immediately answer questions about how they would be deployed.

Iran’s effective closure of the strait, imposed after the U.S. and Israel launched the war on Feb. 28, has shaken global markets.

Ships and seafarers, many on oil and gas tankers and cargo ships, have been stuck in the Persian Gulf since the war began. Crew members have described to The Associated Press watching intercepted drones and missiles explode over the waters, and running low on drinking water, food and other supplies. Many sailors come from India and other countries in South and Southeast Asia.

“They are victims of circumstance,” Trump wrote, and described the effort as a humanitarian gesture “on behalf of the United States, Middle Eastern Countries but, in particular, the Country of Iran.” But he sounded a warning: “If, in any way, this Humanitarian process is interfered with, that interference will, unfortunately, have to be dealt with forcefully.”