Trevor Reed's father advocates outside White House for other detained Americans

The father of Trevor Reed, the American freed from Russia in a prisoner exchange last week, on Wednesday demonstrated outside the White House, calling for the Biden administration to help other Americans held hostage overseas, including two U.S. citizens still detained in Russia, Paul Whelan and WNBA star Brittney Griner.

Trevor Reed, a 30-year-old former Marine, was released last week after nearly three years in detention in Russia, where he was imprisoned on charges that his family and the U.S. government said were trumped up.

He arrived home in Texas last Thursday after being traded for a Russian pilot who had been serving a lengthy sentence in the U.S. for a drug-smuggling conviction. Reed is currently at a military base in San Antonio, receiving counseling and support as part of a reintegration program.

Despite reuniting with his son less than a week ago, Reed's father Joey Reed and his daughter, Taylor Reed, travelled to Washington, D.C., Wednesday to join the demonstration with families of Americans detained in several countries, including Venezuela, Iran, China, Rwanda.

Joey Reed said he had come to urge the Biden administration to repeat what it had done for his son and to put a spotlight on the cases of the families of other detainees.

"We think there's at least 16 cases of detainees and hostages where an exchange would bring them home tomorrow," Reed told ABC News.

He also called on President Joe Biden to meet with the families of other hostages as he did with the Reeds, saying he felt that had been pivotal in persuading the administration to go ahead with the exchange that freed his son.

"We believe that was the complete tipping point was when we met with him," he told ABC News. "He's a personable guy. You know, he's compassionate, kind. Meet with these families like they met with us."

Joey Reed said he had come at the insistence of his son, who is passionate about freeing Whelan, the other former U.S. Marine still held in Russia and who was not part of last week's prisoner exchange.

Reed's release has renewed focus on the cases of Whelan and Griner, who the U.S. government believes were seized by Russia as bargaining chips.

Whelan has been detained in Russia since 2018 and is currently in a prison camp, sentenced to 16 years on espionage charges that the U.S. government and his family say were fabricated.

Griner was arrested at a Moscow airport in February when Russian police alleged they found vape cartridges in her luggage containing hashish oil, a substance illegal in Russia. This week, the State Department reclassified Griner as "wrongfully detained," a designation that allows it to begin negotiating for her release and disregards the Russian criminal case against her.

Reed was freed in an exchange for Konstantin Yaroshenko, a Russian cargo plane pilot who was jailed in the U.S. in 2011, after he was seized in a DEA sting operation and convicted of plotting to smuggle large quantities of cocaine.

Since 2018, Russia had repeatedly floated Yaroshenko as a possible candidate for a prisoner trade for Reed and Whelan. But Russia has also pressed for Viktor Bout, the Russian arms dealer dubbed "the Merchant of Death," who is currently serving a 25-year sentence in the U.S. on drugs and terrorism charges.

Most experts believe Bout -- one of the world's most notorious arms dealers -- is a more difficult trade for the U.S. to accept.

The U.S. is generally reluctant to make prisoner exchanges in hostage case out of a fear of encouraging hostile governments to seize more Americans.

But Joey Reed said his son's case showed the U.S. could be more open to making exchanges if it can get Americans home.

"We just want a trade so they can bring Paul Whelan and Brittney Griner home tomorrow. And we hope that they're working, towards that and that Trevor was just the beginning of a lot of Americans being repatriated with their country and their families," Joey Reed said.

Whelan's sister, Elizabeth Whelan, was also at Wednesday's demonstration and said it was "wonderful" Reed had been released and gave her hope for her brother.

"I do think Trevor Reed's release showed that sort of trade was possible. But I think mostly to us it signaled that tools are available," she said. "So, we're just asking the White House, the administration to do whatever is [possible], use whatever tools are at their disposal to bring Paul home. And the same goes for everyone.

She said she had met with national security adviser Jake Sullivan at the White House before the demonstration and that the meeting had been encouraging.

Asked about the efforts to free detained Americans, State Department spokesman Ned Price on Wednesday said, "What I can say is that we are doing everything we can -- almost all of it unseen, almost all of it unsaid in public -- to do everything we can to advance the commitment that President Biden has to see these Americans who were wrongfully or unjustly detained around the world -- or in some cases held hostage around the world -- brought home."

Among the families represented the event were several whose relatives are held in Venezuela, including Alirio and Jose Luis Zambrano, Jorge Toledo, Tomeu Vadell, Matthew Heath, Jose Angel Pereira, Airan Berry and Luke Denman.

Relatives of Siamak and Baquer Namazi, and Morad Tahbaz, also called for help in freeing them from Iran.

One by one the families stood at a microphone and described the pain of struggling to free their loved ones and pleaded with the Biden administration to act urgently. Several said, Reed's release had given them hope.

Neda Shargi, whose brother, Emad, is serving a 10-year sentence in Iran, addressed Reed directly, saying: "If Trevor is watching this we are so grateful to you for being strong enough to come back. And for having your parents here. Trevor, it's because of you that we have hope."

ABC News' Shannon Crawford contributed to this report.