HARTFORD — Bipartisan legislation closing gaps in a program giving visa privileges to citizens of 38 nations has improved security for Americans, Sen. Chris Murphy said Tuesday.

The junior Democratic senator told reporters at a state Capitol press conference that the legislation imposing restrictions on the visa waiver program "greatly enhances the security of this country."

The measure, which passed the House 407-19 earlier this month, was included in federal spending legislation President Barack Obama recently signed into law.

"This is a huge security gap for the U.S. that we've now begun to close," Murphy said.

As many as 20 million people enter the U.S. annually without screening, he said.

Limiting the waiver program, he said, promotes security more effectively than restricting refugees fleeing Syria, which has been wracked by civil war for nearly five years. A spokeswoman said Murphy supports resettling more refugees in Connecticut and that "every state should do its part" if necessary.

Debate over U.S. refugee policy has generally been partisan, with Republican governors favoring restrictions and Democrats, such as Gov. Dannel P. Malloy, welcoming refugees. Murphy, a member of the Senate Foreign Relations Committee, said refugees face higher hurdles to enter the U.S.

"Refugees are subject to the strongest security screening," Murphy said.

Instead, greater security threats could potentially be related to the visa waiver program, he said.

Obama and lawmakers acted soon after the Nov. 13 terrorist attacks in Paris that killed 130 people, he said. The killings exposed weaknesses in European border security, and Murphy said lawmakers were concerned that Europeans who belong to a "radicalized group" could use the waiver program to enter the U.S.

Polls have shown increasing anxiety among the U.S. public since the attacks in Paris and, particularly, in San Bernardino Dec. 2, when a radicalized couple killed 14 people.

"There's certainly a heightened level of fear in Connecticut," Murphy said. "We must respond."

The visa waiver program allows citizens of participating countries to travel to the U.S. without a visa for stays of up to 90 days for tourism or business if they meet certain requirements.

The new law requires governments of countries in the visa waiver program to share counter-terror information with the U.S. or face expulsion from the program. Visa waiver countries also must issue "electronic passports" that contain chips with detailed information.

In addition, the law makes ineligible for the visa waiver program anyone who has recently traveled to Iran, Iraq, Syria or Sudan, Murphy said. He cited a large al-Qaida presence in Iraq and Iran's history of state sponsorship of terrorism.

The new law also applies to dual nationals with citizenship in those countries. The change, which has drawn criticism, could make travel to the United States more difficult for Iranian-Americans or for Europeans who do business in Iran. It has also raised questions about whether it may violate the recently negotiated nuclear agreement with Iran, which calls for lifting of economic sanctions against Iran.

Murphy said he backed the measure despite the dual citizenship provision, which he said is "going too far." He said he'd also like to see deadlines imposed on participating countries to spur improved sharing of law enforcement information.

He also criticized European nations, with the exception of France and Belgium, which have been cracking down on terrorist cells since the Paris attacks. "Europeans have not taken as seriously the security concerns as the United States," he said, citing the failure to share law enforcement data for no-fly lists.

Murphy also said Iraqi success retaking Ramadi and driving out fighters of the Islamic State group demonstrates that Obama's policy of air strikes coupled with tactical help from advisers is working. "This is proof that the president's strategy is working," he said.