A U.S. blockade targeting Iranian-linked shipping could expand globally if Tehran does not change its behavior, Senator Lindsey Graham warned.

Axar.az reports, citing CBS, Graham said he expects the current maritime restrictions to remain in place and potentially widen significantly.

“I not only expect this blockade to stay in place until Iran shows a commitment to change their ways, I expect the blockade will be growing and that it could become global soon,” Graham wrote on X.

The comments came after U.S. forces intercepted and boarded the sanctioned oil tanker M/T Tifani in the Indian Ocean on Tuesday — the first such boarding outside the Middle East since the current conflict began. The vessel was carrying Iranian crude, according to U.S. officials.

Graham warned that any actors assisting Iran’s oil exports would be taking serious risks. “To those assisting or thinking about assisting the Iranian regime in distributing its oil, which provides resources for terrorism, you do so at your own peril,” he wrote.

In his post, Graham also praised the administration’s strategy, saying the blockade is “having a strong effect” on Iran’s ability to fund what he described as state-backed militant activity. He added that this represents “the best chance since 1979” to change Tehran’s behavior, while expressing hope that the outcome could still be achieved through diplomacy.

The remarks highlight growing momentum in Washington behind using maritime enforcement and sanctions pressure as a central tool in the U.S. approach to Iran, even as diplomatic efforts remain uncertain.