SANTA ANA, CALIF. >> A group of American citizens and legal residents trying to bring their Iranian spouses and other family to join them in the United States has filed a federal lawsuit saying they are being unfairly blocked by the Trump administration’s travel ban.

The families sued late Monday in federal court in Santa Ana, California, saying they have waited months for waivers to be able to be reunited, but the U.S. government hasn’t issued them.

Escalating tensions between the United States and Iran cause the families additional stress, and they fear they could be separated indefinitely.

“They don’t have any other options, and so the only hope they have is the court. Otherwise, they could be in this indefinitely,” said Curtis Morrison, an attorney for the plaintiffs.

An official at the State Department declined to comment on pending litigation. A message requesting comment from the Department of Homeland Security was not immediately returned.

The Trump administration said waivers would be granted on an individual basis to families affected by the ban on travel for citizens of five Muslim-majority countries. But advocates say few waivers have been issued, and there’s no formal system to apply.

The ban affects Iran, Libya, Somalia, Syria, Yemen, North Korea and government representatives from Venezuela.

Some families have sued in California and New York to press for waivers that the Trump administration said would be available so long as issuing them did not threaten national security.

Morrison filed a federal lawsuit earlier this year on behalf seven families trying to bring their relatives from Yemen and said all have since been approved.

He said he often receives frantic calls from plaintiffs in this case who worry about rising tensions between Washington and Iran. Tensions have been rising for weeks over Trump’s decision to pull the United States out of Iran’s nuclear agreement with world powers last year and impose sweeping sanctions on the country.

Plaintiff Farzan Nematollah, a U.S. citizen who lives in Southern California, worries about how he will care for his Iranian wife if conditions worsen between the countries and wants the U.S. government to move quickly on a waiver so the couple can start a family, the lawsuit said.

Plaintiff Shamim Darchini, an American citizen who will soon start a graduate program in San Diego, has been married to her Iranian husband for four years. He was interviewed by a consular officer two years ago, and since then, they have been waiting.

Darchini visits him on vacation, but she said the prolonged separation has left her sleepless and stressed. She has tried asking the consulate, pressed for action on social media and enlisted help from her senator’s office and said she sees no end in sight.

“It is a nightmare,” she said. “I really don’t know what I have to do.”