An Iranian oil tanker that's been at the center of a diplomatic drama between the United States and Iran is back on the move six weeks after being seized off the coast of Gibraltar.

The Grace 1 was seized by British authorities in July at the request of the U.S. due to suspicions that it was bringing oil to Syria in violation of European Union sanctions.

At a cancer treatment center in Iran's capital of Tehran, a doctor's fight to treat her cancer patients has become harder. As U.S. sanctions sink in, the flow of medicine and medical supplies in Iran appears to have slowed — and the reasons are difficult to pin down.

Dr. Mastaneh Sanei, an oncologist at the Roshana Cancer Center, says she's treating patients without the benefits of consistently functioning equipment and a reliable supply of drugs.

With the right treatment, she says, "you may not cure these patients, but they have the chance to prolong survival."

After a stretch of relative peace in Hong Kong, a standoff between protesters and riot police became violent again on Saturday.

Police fired tear gas after pro-democracy demonstrators blocked roads with barricades made of bamboo sticks and hurled bricks, in the district of Kwun Tong.

In a statement, police said protesters paralyzed traffic and affected emergency services in the area near a police station.

Fresh Air Weekend highlights some of the best interviews and reviews from past weeks, and new program elements specially paced for weekends. Our weekend show emphasizes interviews with writers, filmmakers, actors and musicians, and often includes excerpts from live in-studio concerts. This week:

President Trump arrived in France for the annual Group of Seven summit, with the flagging global economy and ongoing trade war with China framing his visit, and the meeting potentially further exposing deep rifts between the U.S. and other countries over trade and climate change.

Just before leaving Washington, D.C., on Friday, Trump increased tariffs on Chinese imports and threatened to force all American companies to leave China. Upon arriving in Biarritz early Saturday, Trump said via Twitter that he had the authority to do so.