CAIRO (AP) — The U.S. military announced it will begin a blockade of all Iranian ports and coastal areas on Monday, a step down from President Donald Trump’s earlier vow to entirely block the strategic Strait of Hormuz as early reports indicated that ships had stopped crossing the waterway.

The move came after marathon U.S.-Iran ceasefire talks in Pakistan ended without an agreement, and it set the stage for a showdown as Iran responded with threats on ports in the Persian Gulf and the Gulf of Oman.

“Security in the Persian Gulf and the Sea of Oman is either for everyone or for NO ONE,” according to the Islamic Republic of Iran Broadcasting, IRIB. “NO PORT in the region will be safe,” the Iranian military said.

U.S. Central Command announced the blockade would begin on Monday at 10 a.m. EDT, or 5:30 p.m. in Iran, and would be “enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman.” CENTCOM said it would still allow ships traveling between non-Iranian ports to transit the strait, a step down from the president’s earlier threat to blockade the entire strait.

The announcement of the blockade halted the limited ship traffic that resumed in the strait since the ceasefire, said an early report from Lloyd’s List intelligence. Marine trackers say over 40 commercial ships have crossed since the start of the ceasefire, down from roughly 100 to 135 vessel passages per day before the war.