Emma Ashford notes  Trump’s obliviousness to the costs of siding with the Saudis and Emiratis in the Qatar crisis:
Indeed, despite these concerns – and despite the efforts of Tillerson, Mattis and others to mediate the dispute, and to walk back the President’s rash tweets – Trump himself appears determined to publicly take the Saudi side in this dispute and force unity within the GCC. In doing so, he risks raising regional tensions, and complicating the anti-ISIS campaign that was the cornerstone of his campaign.
Foreign policy often requires trade-offs. It is no doubt possible that long-term pressure from regional states may induce Qatar to scale back the scope of its foreign policy. But this will come at the cost of other U.S. foreign policy objectives in the region.
The underlying problem with Trump’s handling of the crisis is that he has mistaken the Saudi-led bloc opposed to Qatar for reliable partners in combating jihadism, and so he accepts that their punitive measures against Qatar are proof of their willingness to follow through on supposed commitments made in Riyadh last month. Because he has embraced these client states so fully, he doesn’t appreciate that he is being used to provide their vendetta with a U.S. stamp of approval. He seems to think that the Saudis and their allies are pursuing a U.S.-guided agenda when they are pursuing their own goals without regard to our interests. This is why he keeps thanking King Salman and the Saudi government, but his gratitude–like his support–is seriously misplaced.
The Saudis and their allies are actively undermining U.S. policies in the region, and the president congratulates them on their good work. They single out Qatar to settle scores with them over other issues, but dress up the score-settling as counter-terrorism and Trump believes it without question. The trouble isn’t just that he doesn’t grasp the trade-off being made, but that he actually thinks the U.S. is benefiting greatly from the Saudi-led bloc’s self-serving adventurism. Like many other hawks who conflate U.S. interests and those of bad regional clients, Trump can’t perceive the trade-off being made because he refuses to see the divergence of interests clearly on display.
The danger for the U.S. and the wider region is that the small emirate is not going to roll over so easily, and that means that the crisis is going to fester and probably grow worse over time. Qatar’s foreign minister was adamant  about this earlier in the week:
“No one has the right to intervene in our foreign policy,” Sheikh Mohammed said.
He also rejected “a military solution as an option” to resolving the crisis, and said Qatar could survive “forever” despite the measures taken against it.change_me
“We are not ready to surrender, and will never be ready to surrender the independence of our foreign policy,” he told reporters later, adding: “No one will break us.”
Backing up Qatar’s determination to resist is the fast-tracked approval of Turkish military forces to be deployed to Qatar. Erdogan signed  the legislation authorizing the deployment this week:
President Tayyip Erdogan called for the lifting of a blockade on Qatar on Friday after approving legislation on deploying Turkish troops there, as the Gulf state faces isolation imposed by fellow Arab states over its alleged support for terrorism.
Erdogan vowed to keep supporting Qatar after his rapid approval of the bill, pushed through parliament on Wednesday, and he rejected accusations that it supported terrorism.
Turkish support makes it less likely that Qatar will yield to the maximalist demands being made of them. Instead of discouraging the Saudi-led bloc from another ill-considered course of action, vocal U.S. backing  is likely to encourage the Saudis and their allies to use more aggressive measures. Considering their disastrous miscalculation regarding intervention in Yemen  two years ago, we should not trust that their leaders will have the good judgment to back down:
“Most worrying is that Saudi Arabia and the U.A.E. may repeat the mistakes that were made when the Saudi leadership decided to launch a war in Yemen,” said Yezid Sayigh, a Beirut-based senior fellow at the Carnegie Endowment for International Peace. “They had no clear political strategy, based their action on false assumptions, have incurred heavy financial costs and a growing human toll, and are probably now worse off in terms of their security.”
In his remarks  this afternoon, Trump didn’t just voice support for the Saudi-led punitive policy, but claimed that these governments had approached him and received his approval beforehand:
Trump said the nations that imposed the blockade — including Saudi Arabia, Egypt and the United Arab Emirates — came to him in the wake of his conference in the region to discuss “confronting Qatar over its behavior.”
“So we had a decision to make: Do we take the easy road or do we finally take a hard but necessary action?” Trump said.
Elsewhere in Trump’s statement, he issued what could easily be interpreted as an ultimatum and not-so-veiled threat when he said, “They have to end that funding.” This rhetoric of what Qatar “has to” do implies that there may be even more severe consequences for them if they don’t comply. That is very likely to be interpreted as an endorsement of escalation against Qatar, which is exactly what the U.S. doesn’t need and should be working hard to prevent.
The central problem in all of this is that Trump believes the Saudi-led bloc is acting to advance our interests when they are really just pursuing their own rivalries at our expense, and by tying his foreign policy so closely to the Saudis he has blinded himself to the reality that he is being used by them for reasons that have nothing to do with fighting terrorism. Trump is putting the U.S. fully on one side of an internecine quarrel in which none of the governments involved deserves our support, and in the process he is putting our foreign policy in hock to reckless despotic clients.