President Trump on Friday advocated for a "larger, tougher and more specific" travel ban in response to a bomb explosion in London’s subway system.

Trump in a string of tweets called the bombing an attack “by a loser terrorist” and suggested British authorities did not do enough to prevent it.

"Another attack in London by a loser terrorist,” he tweeted. “These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!”

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Trump then sent another message about the ban, writing ”the travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct!"

A device exploded on a rush-hour train in southwest London early Friday, injuring at least 23 people. Police are treating the incident as a terrorist attack. They have identified a suspect, but have not released a name.

The explosion at the Parsons Green Underground station is the latest in a series of terror attack that have shaken Great Britain this year.

“It’s a terrible thing,” Trump told reporters at the White House later Friday. “It keeps going and going, and we have to be very smart and we have to be very, very tough—perhaps we’re not nearly tough enough.”

Trump’s response angered British authorities, since he appeared to reveal certain information about the attack before they did.

"I never think it is helpful for anyone to speculate in what is an ongoing investigation," British Prime Minister Theresa May told reporters in London when asked about the president’s comments.

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In Washington, Trump said he had been briefed on the attack and planned to call May later Friday.

The president’s pointed comments could be geared toward his supporters, many of whom are angry with his efforts to strike an immigration deal with Democrats.

The agreement he discussed with Democratic leaders would provide relief for young immigrants living in the U.S. illegally in exchange for tougher border security measures. But that might not include Trump’s proposed wall along the U.S.-Mexico border, a key campaign promise, which he said would come “later.”

Seeking to reassure supporters, Trump tweeted Friday that, “CHAIN MIGRATION cannot be allowed to be part of any legislation on Immigration!”

Friday isn’t the first time Trump has irked British leaders with his administration’s response to terror attacks in their country.

The president attacked Sadiq Khan, London’s first Muslim mayor, in June after he urged city residents to remain calm after a terror attack on the London Bridge killed seven.

“At least 7 dead and 48 wounded in terror attack and Mayor of London says there is ‘no reason to be alarmed!’” Trump tweeted at the time.

The U.K. temporarily stopped intelligence sharing with the U.S. after a May attack in Manchester, when photos showing the grisly aftermath of the strike were published in The New York Times.

Trump pledged to investigate leaks coming from government agencies after British authorities threatened to cut off intelligence sharing altogether.

On Friday, the president once again chimed in on how he thinks Britain should respond to terror attacks.

“Loser terrorists must be dealt with in a much tougher manner. The internet is their main recruitment tool which we must cut off & use better!” Trump tweeted.

“We have made more progress in the last nine months against ISIS than the Obama Administration has made in 8 years. Must be proactive & nasty!” he added.

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Trump’s tweets came a few days after the Supreme Court agreed to lift restrictions on the travel ban until further notice, allowing the administration to continue barring most refugees under the ban.

But the policy still faces legal challenges. Hawaii is suing the Trump administration over the travel ban, which bars citizens from six majority-Muslim countries from entering the U.S. and temporarily halts the country's refugee resettlement program.

Hawaii urged the court to uphold a ruling from the 9th Circuit Court of Appeals and continue to allow refugees into the U.S.

- This story was updated at 11:22 a.m.