Look closely at security

As more becomes known about the three Islamic terrorists who went on a killing spree last weekend in London, troubling questions are being raised about British authorities’ ability to anticipate and prevent such violence.

British intelligence agencies were familiar with at least two of the attackers. One had told authorities he “wanted to be a terrorist.” Another was such a well-known supporter of Islamic terrorism that he had been filmed in a documentary titled “The Jihadis Next Door.” In 2015, his neighbor reported to police that the man had been recruiting followers for the Islamic State organization.

As the investigation proceeded earlier this week, British Foreign Secretary Boris Johnson wondered aloud how the terrorists “slipped through our net.”

Prime Minister Theresa May already has said it is time for the British to rethink their tolerance for extremists in their midst.

All this should disturb the British. It also should cause Americans to ask how effective our homeland security measures have been.

It is known they have prevented some terrorist attacks, probably many more than the press and public know.

But have years of such successes resulted in better homeland security — or dangerous complacency?

Our intelligence and law enforcement agencies do excellent, praiseworthy work. But it may be time for them, and perhaps Congress, to undertake a realistic assessment of whether our security net needs tightened.