Japan and the United States say they have reached an agreement on trade and tariffs after months of negotiations. US President Donald Trump announced the deal on social media, calling it "massive" for both countries.

Trump said the deal involves what he calls "reciprocal tariffs" on Japanese imports set at 15 percent. That's down from the 25 percent he had threatened would take effect from August 1st.

Trump says Tokyo agreed to trade goods such as automobiles, rice and other agricultural products, and invest 550 billion dollars into the US.

He claimed the deal will create hundreds of thousands of jobs.

Trump spoke about the deal at an event shortly after posting the announcement.

"It's a great deal for everybody," he said. "I always say it has to be a great deal for everybody. It's a great deal, a lot different from the deals in the past ... But we're doing really well as a country with strong, we have a lot of money flowing in."

Sources close to the Japanese government say that the two countries agreed to expand the ratio of rice imports from the US.

Japan imports about 770,000 tons of tariff-free rice every year on a mandatory basis under a system called "minimum access."

Sources say that Japan will increase the percentage of US rice it imports within that framework.

Japanese Prime Minister Ishiba Shigeru told reporters that he will receive reports on the details, and will examine them closely. He expressed confidence that the deal will help protect Japan's national interests, foster job creation alongside the United States, and help both countries play key roles on the world stage.

The agreement comes after Japan's chief tariff negotiator, Akazawa Ryosei, arrived in Washington for an 8th round of talks this week. His team was racing to strike a deal before the August 1st deadline.