US authorities said two people with ties to the Islamic State (ISIS) group are due in court Friday in California and Texas, including a migrant from Syria who lied about his travels there.
The arrests come amid heightened security in the United States following last month's assault by a Muslim couple in California that left 14 people murdered, and the November ISIS terror attacks in Paris that murdered 130 victims.
There is also growing pressure for more scrutiny of migrants from war-ravaged Syria, amid fears that terrorist swill infiltrate the massive influx that US President Barack Obama is pushing for.
Aws Mohammed Younis al-Jayab, an Iraq-born Palestinian Arab arrested Thursday who came to the United States from Syria as a refugee in 2012, traveled to Syria the following year where he fought with various terror groups, according to a criminal complaint.
One of those groups was Al Qaeda affiliate Ansar al-Islam (Partisans of Islam), which once operated in both Iraq and Syria.
Listed as a terrorist organization by the United Nations and the United States, its Iraq faction has since merged with the Islamic State group, though some of its Syrian fighters rejected ISIS.
But US Attorney Benjamin Wagner claimed that "while (Jayab) represented a potential safety threat, there is no indication that he planned any acts of terrorism in this country."
Another Iraqi-born Palestinian, Omar Faraj Saeed Al Hardan, was indicted Wednesday in Texas for providing material support to the ISIS group. He is due in court Friday for an initial appearance.
Hardan, 24, was charged with one count each of attempting to provide material support to ISIS, procurement of citizenship or naturalization unlawfully and making false statements.
Texas Governor Greg Abbott and other local officials said Hardan's arrest backed their calls for a refugee ban.
"This is precisely why I called for a halt to refugees entering the US from countries substantially controlled by terrorists," he said.
The state's Attorney General Ken Paxton called the arrest a "troubling revelation."
"The arrest in Houston of an Iraqi refugee for suspicion of terrorist activities is a troubling revelation - especially in light of the president's insistence on placing further refugees in Texas," he said.
"My office will continue to press for the right of Texans to ensure that terrorists are not being placed in our communities."
Hardan, who lives in Houston, was granted legal permanent resident status in 2011, two years after entering the United States.
According to the indictment, he provided training, expert advice and assistance to ISIS.
He also lied on his formal application to become a naturalized US citizen, saying he was not associated with a terror group despite having been associated with ISIS members and sympathizers throughout 2014.
During an October 2015 interview, Hardan is also said to have falsely claimed he had never received weapons training of any kind when he had in fact learned to use machine guns.
He faces up to 53 years in prison and a $250,000 fine if convicted on all charges.
The complaint against Jayab, the 23-year-old Californian man, states that he planned his trip to Syria through online contact with various individuals and arrived there via Turkey in November 2013.
His online messages, copies of which are contained in the complaint, indicate he was based in the northern Syrian city of Aleppo, where he boasted about his activities with Ansar al-Islam, claiming he had also fought with the group while living in Iraq.
At one point, he apparently expressed interest in joining ISIS.
"I have been thinking of joining the State and abandon(ing) the al-Ansar," he says in one online message to an unidentified individual.
Authorities say Jayab crossed from Syria back into Turkey on January 17, 2014 and returned to California six days later.
He told immigration officials at the time that he had traveled to Jordan and Britain.
When further questioned by authorities about his travels, he stated he had gone to Turkey for a vacation and denied going to Syria.
Jayab, who also faces an initial court appearance on Friday, in California's state capital Sacramento faces up to eight years in prison and a $250,000 fine if convicted of making a false statement involving international terrorism.
AFP contributed to this report.