WASHINGTON — President Donald Trump on Monday denied his immigration order was to blame for the chaos at the nation’s airports over the weekend, instead pointing to computer glitches, protesters and even the “tears of Senator Schumer.”

“There is nothing nice about searching for terrorists before they can enter the country,” Trump wrote in a series of early morning tweets. “This was a big part of my campaign. Study the world!”

In another tweet, Trump defended his decision to take swift action on his proposed travel ban, saying there are “a lot of bad ‘dudes’ out there.”

“If the ban were announced with a one week notice, the ‘bad’ would rush into our country during that week,” Trump said.

Trump’s order temporarily suspends all immigration for citizens of seven majority Muslim countries for 90 days.

But he enters his second week in office amid a global backlash to his policies. European Union officials denounced his immigration order as a dangerous embrace of isolationism and inequality, while the international aid group Doctors Without Borders accused Trump of keeping people “trapped in war zones, directly endangering their lives.”

In Iraq, two lawmakers there said the Iraqi parliament has approved a “reciprocity measure” restricting the entry of Americans into Iraq.

Meanwhile, it’s unclear how Trump’s order would make the nation safer. The order does not address homegrown extremists already in America, a primary concern of federal law enforcement officials. And the list of countries in Trump’s order doesn’t include Saudi Arabia, where most of the Sept. 11 hijackers were from.

The president tweeted early Monday that only 109 out of 325,000 “were detained and held for questioning” following his executive order to bar individuals from seven Muslim-majority countries. The Homeland Security Department has used 325,000 as the number of international air travelers who arrive every day to the U.S.

“Big problems at airports were caused by Delta computer outage, protesters and the tears of Senator Schumer,” he added.

Trump was referring to a Delta systems outage Sunday night that led to departure delays and cancellations of at least 150 Delta flights. However, the chaos started Saturday as protesters packed some of the country’s major airports to demonstrate against the executive order.

Democratic Sen. Chuck Schumer tweeted Friday that “Tears are running down the cheeks of the Statue of Liberty” over the ban.

Trump has defended his order by saying it’s not a “Muslim ban.”

In a background call with reporters Sunday, a senior administration official declared the order’s implementation “a massive success story,” claiming it had been done “seamlessly and with extraordinary professionalism.”

Yet there appeared to be widespread confusion among authorities tasked with carrying out the order and how it would be applied to certain groups, like U.S. legal permanent residents.

Homeland Security Secretary John Kelly issued a statement Sunday saying that, absent information indicating a serious threat to public safety and welfare, residency would be a “dispositive factor in our case-by-case determination.” That means citizens of the seven countries who hold permanent U.S. residency “green cards” will not be barred from re-entering the U.S., as officials had previously said. It remains unclear what kind of additional screening they will now face.

“You have an extreme vetting proposal that didn’t get the vetting it should have had,” said Ohio Sen. Rob Portman, who urged the new president to “slow down” and work with lawmakers on how best to tighten screening for foreigners who enter the United States.