In the hours after the London terrorist attack, President Trump took to his favored platform, Twitter, to deliver a stream-of-consciousness response. He repeated his call for a “travel ban” on visitors from six predominantly Muslim countries. And he warned against political correctness. “If we don’t get smart it will only get worse,” he said. “Do you notice we are not having a gun debate right now?” he added, in a puzzling non sequitur. “That’s because they used knives and a truck.”

For critics of Trump, his tweets betray a buffoonish approach to national security that will only make terrorism worse. His proposed travel restrictions will only aid recruitment for the Islamic State, they say. His demand, during a speech in Saudi Arabia, two weeks ago, for Muslim heads of state to do more ignores the reality that, since the September 11th attacks, vastly more Iraqi and Afghan soldiers and police than American service members have died battling extremists. And Trump’s loosening of Pentagon rules surrounding the use of air strikes and commando raids against the Islamic State, Al Qaeda, and other terrorist groups will only lead to more civilian deaths, fuelling resentment and reprisals.

Yet several counterterrorism experts, including some who worked under President Obama, admitted to me, in private conversations recently, that new approaches to combat extremism are badly needed, and that Trump has a chance to take steps that could prove effective. The problem is that, just as in other policy areas, Trump threatens to undermine his own counterterrorism strategy with his bellicose mode of communication. “His rhetoric belies a fundamental lack of understanding of the greater nuances of the issue, and in particular the root causes that have allowed ISIS to prey on the vulnerable and disaffected in our communities,” a former senior counterterrorism official told me on Sunday. “His immediate call for a ban on Muslims in the wake of the most recent attack and throughout his short time as President is arguably more likely to alienate Muslim Americans, and thus potentially inspire further acts of homegrown terrorism, than it is to prevent terrorists from entering the country and perpetrating terrorist acts.”

Several former officials said that they generally supported Trump’s cruise-missile strike on a Syrian airbase, in April, after U.S. intelligence officials said Syrian government forces carried out a chemical-weapons attack that killed scores of people, including children. The counterterrorism experts told me that the strikes showed American allies and adversaries alike that Trump would be more willing to use force than Obama, who critics said lost credibility, in 2013, when he failed to respond militarily to a chemical-weapons attack by the Syrian government that killed hundreds.

Trump also appears to be continuing to emphasize a core element of Obama’s strategy, which is that countries in the region should lead the fight. The Trump Administration’s recent hundred-and-ten-billion-dollar arms sale to Saudi Arabia is similar to one carried out under the Obama Administration, which worked to build up the military, intelligence, and police capabilities of allies in the region in a much less public way than Trump has thus far. Obama also embraced the use of covert drone strikes, intense vetting of visa applicants, and the stepped-up use of surveillance technologies, angering many on the left.

Trump has opportunities to make progress in areas where Obama struggled, such as developing consensus regarding new communications technologies, the officials said. Terrorists are increasingly using sophisticated encryption techniques to mask their communications, but Obama Administration officials were unable to reach an agreement with technology companies on ways to curb such uses that balanced privacy and public-safety concerns. Now Trump or his aides could try to quietly fashion some type of compromise.

Trump has yet to unveil a comprehensive strategy from his Administration to fight terrorism. As Dexter Filkins recently wrote, in a Profile of Defense Secretary James Mattis, some officials fear that Trump will bluster about terrorism in public but privately delegate strategy to the military. Some U.S. military commanders welcomed an end to what they viewed as micromanagement and risk aversion by the Obama White House, but they fear that the inexperienced Trump will become overly reliant on military force.

But where Trump has been most dangerous, former counterterrorism officials told me, is in his public statements, and the way he has publicly harangued allies—from Muslim leaders to NATO members—often while citing incorrect facts. Now, in the wake of three successful attacks in Britain in three months, the worry is that attacks will occur in the United States as well, and Trump will revert to a pattern of fearmongering. The President could convince Congress to enact new surveillance standards that erode civil liberties but fail to end attacks. Or Trump could publicly vilify Islam, a step that will alienate American Muslims and aid extremist recruiting efforts domestically and internationally. “You end up with the legislation that is bad for everybody,” the former senior counterterrorism official told me. “Bad for counterterrorism and bad for civil liberties.”

Counterterrorism is one area where Trump could take advantage of the bipartisan consensus that exists regarding some anti-terror policies, the officials whom I talked to said. But if the President’s inability to communicate with discipline, accuracy, and nuance continues, he will only alienate allies and inflame enemies.