The United States Sunday reiterated its call for Iran to immediately release U.S. citizens Shane Bauer and Joshua Fattal, two hikers who were sentenced to eight years in prison, after being imprisoned for more two years for allegedly trespassing into Iran, which they deny.

Bauer, Fattal and a third U.S. citizen, Sarah Shourd were arrested on July 31, 2009 while they were hiking in the mountains of northern Iraq while on vacation. They said that if they crossed the border into Iran, it was accidental. Shourd has freed on $500,000 bail last year and returned to the U.S, the Voice of America reported Sunday. Shourd was released for medical reasons and returned to the U.S., but her case remains open in Iran and she may be tried in abstentia.

Iran accused the group of illegally crossing into Iran and committing espionage. Bauer, Fattal, and Shourd and their supporters say they are innocent.

We are deeply disappointed that Iranian judicial authorities have sentenced Shane Bauer and Joshua Fattal to 8 years in prison, U.S. Secretary of State Hillary Clinton said Sunday, in a statement. We continue to call and work for their immediate release -- it is time for them to return home and be reunited with their families.

I join President Obama and the people of the United States in expressing our unflagging support for Shane, Joshua, Sarah and their families during this difficult time, Clinton added.

No Evidence of Guilt

Masoud Shafi, Bauer's and Fattal's attorney said he has seen no evidence of their guilt and will appeal the sentence.

It's a very strange verdict and I was very surprised, said Shafi said, in a phone interview with The Wall Street Journal. But I plan to use every legal means I can to change it, because I believe they are innocent.

Political/Foreign Policy Analysis: Look for the U.S. Government to begin to move its diplomatic and related levers to secure the release of Bauer and Fattal.

Iran, which invented the game of chess, is clearly using Bauer and Fattal as pawns, most likely in an effort to force the release of Iranian operatives held by the United States.

In September, Iran's President Mahmoud Ahmadinejad is scheduled to travel to New York for the opening of the United Nations' General Assembly, and the hope is that third-party nation intermediaries can find ways to convince Iran that it's in their interest to release the two so that they can resume their lives.