Newly obtained congressional data shows hundreds of terror plots have been stopped in the U.S. since 9/11 – mostly involving foreign-born suspects, including dozens of refugees.

The files are sure to inflame the debate over the Obama administration’s push to admit thousands more refugees from Syria and elsewhere, a proposal Donald Trump has vehemently opposed on the 2016 campaign trail.

“[T]hese data make clear that the United States not only lacks the ability to properly screen individuals prior to their arrival, but also that our nation has an unprecedented assimilation problem,” Sens. Jeff Sessions, R-Ala., and Ted Cruz, R-Texas, told President Obama in a June 14 letter, obtained by FoxNews.com.

The files also give fresh insight into the true scope of the terror threat and cover a wide range of cases, including:

  • A Seattle man plotting to attack a U.S. military facility
  • An Atlantic City man using his “Revolution Muslim” site to encourage confrontations with U.S. Jewish leaders “at their homes”
  • An Iraq refugee arrested in January, accused of traveling to Syria to “take up arms” with terror groups

While the June 12 massacre at an Orlando gay nightclub marked the deadliest terror attack on U.S. soil since 2001, the data shows America has been facing a steady stream of plots. For the period September 2001 through 2014, data shows the U.S. successfully prosecuted 580 individuals for terrorism and terror-related cases. Further, since early 2014, at least 131 individuals were identified as being implicated in terror.

Across both those groups, the senators reported that at least 40 people initially admitted to the U.S. as refugees later were convicted or implicated in terror cases.

Among the 580 convicted, they said, at least 380 were foreign-born. The top countries of origin were Pakistan, Lebanon and Somalia, as well as the Palestinian territories.

Both Sessions and Cruz sit on the Senate Judiciary Subcommittee on Immigration and the National Interest, which compiled the terror-case information based on data from the Justice Department, news reports and other open-source information. The files were shared with FoxNews.com.

The files include dates, states of residence, countries of origin for foreign-born suspects, and reams of other details.

Specifically, they show a sharp spike in cases in 2015, largely stemming from the arrest of suspects claiming allegiance to the Islamic State. They also show a heavy concentration of cases involving suspects from California, Texas, New York and Minnesota, among other states.

EXPLORE THE DATA IN THE MAPS AND CHARTS BELOW

The senators say the terror-case repository still is missing critical details on suspects’ immigration history, which they say the Department of Homeland Security has “failed to provide.” Immigration data the senators compiled came from other sources.

Sessions and Cruz asked the president in their letter to order the departments of Justice, Homeland Security and State to "update" and provide more detailed information. The senators have sent several letters to those departments since last year requesting immigration histories of those tied to terror.

“The administration refuses to give out the information necessary to establish a sound policy that protects Americans from terrorists,” Sessions said in a statement to Fox News. 

Asked about the complaints, DHS spokeswoman Gillian M. Christensen told FoxNews.com the department “will respond to the senators’ request directly and not through the press.”

“More than 100 Congressional committees, subcommittees, caucuses, commissions and groups exercise oversight and ensure accountability of DHS and we work closely with them on a daily basis. We’ve received unprecedented requests from a number of senators and representatives for physical paper files for more than 700 aliens,” she said, adding that officials have to review each page manually for privacy and other issues.  

Cruz ran unsuccessfully this year for the Republican presidential nomination. Sessions, an ardent critic of the administration’s immigration policies, is supporting presumptive GOP nominee Trump.

The allegations detailed in the subcommittee’s research pertain to a range of cases, involving suspects caught traveling or trying to travel overseas to fight, as well as suspects ensnared in controversial sting operations which civil-liberties groups including the ACLU have criticized.

In a 2014 report, Human Rights Watch said nearly half of the federal counterterror convictions at the time came from “informant-based cases,” many of them sting operations where the informants played a role in the plot.

The report said: “In some cases the Federal Bureau of Investigation may have created terrorists out of law-abiding individuals by conducting sting operations that facilitated or invented the target’s willingness to act.”

But even in some of those cases, federal agents got involved after learning of a serious suspected plot. In the case of the Seattle suspect, Abu Khalid Abdul-Latif, authorities said he approached someone in 2011 about attacking a military installation. That citizen alerted law enforcement and worked with them to capture Latif and an accomplice. 

FoxNews.com’s Liz Torrey contributed to this report.