Vice Admiral Brad Cooper, the deputy commander of U.S. Central Command who is nominated to be the next CENTCOM head, said at his Senate confirmation hearing on Tuesday that the United States is prepared for the possibility that Iran will attempt to place mines in the Strait of Hormuz to close off the strategic waterway.

The Iranian parliament approved a move earlier this week to close the strait, but that decision would be dependent on the approval of the Iranian leadership, and it’s not clear whether the ceasefire between Israel and Iran might hold off such a move. Around a third of the world’s oil supply passes through the strait, which connects the Persian Gulf and several Gulf states to the Arabian Sea.

The incoming CENTCOM leader, who previously led naval forces in CENTCOM and the Fifth Fleet based out of Bahrain, told the Senate Armed Services Committee that the U.S. “has sufficient capacity and capability to handle the threat” of mining the Strait of Hormuz, and that it is keeping a close eye on Iranian movements that would signal such an operation is occurring.

“It would certainly be important for us to watch what they’re doing and attempt to both anticipate and then react faster than the threat,” Cooper said. “It’s a significant threat. It’s a known threat, and one that we’re watching.”

Cooper acknowledged that the potential shutdown of the Strait of Hormuz would have “significant” impacts on U.S. operations in the Middle East. He said it would be a “complex problem,” given that Iran has stockpiles of thousands of mines, and noted that “historically in mine warfare, nothing happens quickly,” saying the operation would be a matter of “weeks and months, not days.”

Cooper said that U.S. and Israeli strikes, and particularly Israel’s successes against Iran and its proxies, have weakened and degraded Iran significantly, but added that Iran remains the primary destabilizing agent in the region and a sponsor of global terrorism.

“They possess considerable tactical capability, one element of which we saw yesterday,” Cooper said, referring to Iranian missile barrages at U.S. bases in Qatar and Iraq. “We’ve got to be in a three point stance, ready to go every single day. “

Pressed repeatedly by Democrats on whether the U.S. is planning for a ground invasion or for regime change in Iran, Cooper declined to discuss specifics in public, stating that his role is and would be to provide options to the administration’s civilian leadership and to prepare for various potential scenarios.

Cooper added that “deterring Iran and its proxies … is a critical element of our national security,” noting as well that some of the Iranian-aligned militia groups in the region, as well as the Houthis, remain an active threat. He highlighted that Iranian proxies have attacked Americans around 500 times in the past 20 months.

Lt. Gen. Alexus Grynkewich, the director of operations for the Joint Chiefs of Staff and former director of operations for CENTCOM, who was testifying alongside Cooper, said that “the Houthis are likely to be a persistent problem that we’ll be dealing with in the future a few times again.”

Cooper said it might take several months for normal commercial trade to resume through the Bab-el-Mandeb Strait after the U.S.-Houthi ceasefire agreement was reached last month.

Cooper said that the U.S. is prepared for a range of scenarios should the Houthis break the ceasefire. He also warned that the Yemeni terrorist group is “extremely well supplied by the Iranians” and is increasingly entrenching underground.

He added that, learning from Hamas, Iran and other groups in the region, U.S. adversaries entrenching underground is likely to be a growing problem in the future. He highlighted the work of Israel and U.S.-Israeli collaborative efforts to counter this threat.

Cooper emphasized concerns about the growing cooperation between U.S. adversaries such a Iran, China, Russia and North Korea. He expressed particular frustration about the flow, through Iran, of weapons components from China to the Houthis, and China’s longstanding failure to take action against the Houthis.

The vice admiral emphasized that the U.S.’ efforts in Syria going forward will be led by diplomacy and appear to be headed in a positive direction, but added that the U.S. must remain vigilant and active to focus on the ongoing threat from ISIS.

“Stability in Syria can translate into security in the United States,” Cooper said. “And here’s how those dots connect. ISIS thrives in chaos. If the government of Syria, now seven months into their existence, can help suppress that ISIS threat, along with the U.S. forces in the region, that stability helps create our own security. I’m optimistic for the future.”

He argued that now is not the time for the U.S. to be pulling back from the Middle East, and that any drawdown of troops from Syria — which the Trump administration has pursued — should be based on conditions on the ground, emphasizing that the U.S. remains the leader of the international coalition to combat ISIS.

Cooper said that the Abraham Accords and Israel’s incorporation into Central Command “presents extraordinary opportunities to advance security and enhance deterrence” in the region, and that he would continue to work on those relationships — a priority for the outgoing CENTCOM leader, Gen. Erik Kurilla.