"Enough is enough." So said British Prime Minister Theresa May after Saturday's attack in central London.

The murder of seven people by three terrorists was a watershed moment. If May wins in tomorrow's general election, she promises decisive action to protect the public.

The urgency is justified. Some analysts suggest jihadist activity in Britain has risen to the level of an insurgency. Whatever the truth of that, no democracy can long tolerate intimidation of its citizens by a death cult.

Yet British terrorism is a global problem, not merely a national one. The Islamic State's murder entrepreneurialism is worldwide. It is America's chief national security challenge. In Orlando and Manchester, in San Bernardino and Brussels, in Paris and Kabul, and in so many other locales, we have learned that the enemy's appetite for mayhem and murder has no geographic limit.

Neither May's resolve nor the solidarity of the West is sufficient on its own. The evolving terrorist threat requires an evolving response. Just as the Islamic State innovates in order to kill us, so must we innovate to thwart it and destroy it. Congress, the military and the entire U.S. national security establishment must respond with speed and force.

What would this response look like? The most obvious measure is the one President Trump promised: extreme vetting of immigrants. Trump's executive order, still tied up in the courts, is a temporary patch. The ultimate policy won't be country-specific, but will instead better screen all people who want to enter the country. It must ensure a greater degree of certainty that terrorists aren't finding back doors, side doors and windows through which to gain access.

Second, the nation's counterterrorism bureaucracy must be reformed. There's a decent argument that the Department of Homeland Security, created in a rush after 9/11, should be disbanded and qualified DHS officers transferred to the FBI.

The government must also improve recruitment of counterterrorism officials. The current system emphasizes paperwork rather than finding the best applicant. In doing so, it often disregards or slows down acceptance of those people who were born overseas and might therefore be the most helpful. Recruiters should be expected to interview applicants with foreign backgrounds for each open position.

More federal counterterrorism grants should be transferred from urban to rural areas. The Islamic State does not differentiate between supporters in New York City and those in rural Montana. Today we spend billions of dollars on metro police departments that are already well resourced but ignore local police capabilities.

Third, we must improve European intelligence sharing. Terrorist groups see visa waiver programs as a loophole that allows them to come from favored European countries to the United States to carry out attacks. They know that if a terrorist is unknown to European authorities, that so-called "cleanskin" is likely to be unknown to American authorities, too. To identify these terrorists efficiently, European and American governments must share intelligence as soon as a report is available.

Fourth, the federal government must challenge the ideology that sustains jihadist terrorism. To do so, it should reconstitute the U.S. Information Agency. Perhaps funded by reallocations from the international development agency, the revitalized information agency should host controversial debates. It should put respected American imams on stage alongside extremist imams. Our free exchange of ideas is our greatest strength at home. It can be a powerful counterterrorism tool abroad.

Fifth, our surveillance methods must be reformed. Civil libertarians, American Muslims and many voters are skeptical of government surveillance, to put it no more strongly. Congress could increase support for needed surveillance by taking extra measures to prevent abuses. One idea would be to make the process of seeking foreign surveillance warrants more stringent and less likely to be rubber-stamped. This could be done in part by appointing federal judges as defendant representatives in surveillance applications.

By enhancing civil rights protections and foreswearing those easy existing opportunities for inappropriate surveillance, government can earn the respect and credibility it needs to conduct more surveillance where it is appropriate.

The world knows all too well that terrorism is a serious business. It cannot be approached with excessive reliance on tried but habitual investigative procedures that terrorists are constantly learning to circumvent. As the territorial Islamic State faces its downfall in the coming days, Trump and his allies in the West must move now to back up May's resolve. With greater cooperation and more fresh thinking, the world's open and free societies can get a head start on terrorists whose defeat in Mesopotamia and the Levant will throw them into temporary confusion. Determined, swift, entrepreneurial counterterrorism now and a commitment constantly to innovate in the fight against our existential enemy can ensure that we remain a ahead of the killers in years to come.