On this weekend’s broadcast of “Fox News Sunday,” Sen. Tom Cotton (R-AR) reacted to what he called Iran “marching up the escalation chain,” which includes interference with international shipping lanes in the Persian Gulf and the downing of an unmanned U.S. drone in international airspace.

Cotton told host Chris Wallace he was concerned that if the United States didn’t set a “firm set of boundaries,” Iran could attack a U.S. ship or manned aircraft.

Partial transcript as follows:

WALLACE: Well, this week, as we all know, I ran went after and shot down a U.S. Navy and President Trump first ordered and then called off a retaliatory strike.

What do you think of the president’s move?

COTTON: Chris, obviously, I think retaliatory strikes were warranted when we’re talking about foreign vessels on the high seas. I think they’re warranted against an American unmanned aircraft.

What I see is Iran steadily marching up the escalation chain. It started down with threats, it went into an attack on vessels in ports, went into attack on vessels at sea, now to unmanned American aircraft. I fear that if Iran doesn’t have a firm set of boundaries drawn around this behavior, we are going to see an attack on a U.S. ship or U.S. manned aircraft.

This is exactly what we saw in the 1980s, where Iran for four years was allowed to attack ships on the high seas, over 190 attacks in the Iran-Iraq war. Ron Reagan finally lost his patients after one of those mines hit a U.S. Navy frigate and then he launched one of the largest naval engagements since World War II.

I hope that that’s not the case. I hope it is not the case. I hope the president’s statement on Friday and a statement yesterday that we will not tolerate any kind of attack on the American service member anywhere in the region gets through to the leaders in Tehran. I worry, though, that they have a long history of marching up this escalation ladder anytime they face a kind of strategic challenge they face right now, thanks to the administration’s maximum pressure campaign.

WALLACE: You were very critical of President Obama’s failure to enforce his redline against Syria after a chemical attack, saying that it raised questions about how strong U.S. security commitments and statements by the president were. President Trump has repeatedly gone after Mr. Obama on the same thing. Take a look.

(BEGIN VIDEO CLIP)

DONALD TRUMP, PRESIDENT OF THE UNITED STATE: When he didn’t cross that line after making the threat, I think that set us back a long ways not only in Syria but in many other parts of the world because it was a blank threat.

(END VIDEO CLIP)

WALLACE: Does this run the risk of being President Trump’s red line moment?

COTTON: No. Chris, I see some differences between the two situations. First, the President Obama’s Syria policy was a mess. Second, he himself in his words drew that red line and then he failed to enforce it.

Here, President Trump’s Iran policy is working. It’s probably the first time in 40 years where we have the initiative against Iran. One reason they are lashing out is because of a maximum pressure campaign that has driven their economy to near depression levels of activity.

Second, he had not drawn any such red line in his own language. He didn’t take military strikes last week and overt or conventional fashion but he has said very clearly that we will not tolerate — Iran or its proxies making any type of attack on American service members or citizens in the region. And he’s also said that major sanctions are going to be added tomorrow, which is only going to increase the sanctions they already face, which is one very positive results so far of the maximum pressure campaign.