美国有线新闻 CNN 美国会首次推翻奥巴马否决案 美将向伊拉克增兵500人

First up, a historic showdown between the U.S. Congress and the U.S. president. Earlier this month, the House and Senate passed a controversial bill. Its goal was to allow the families of terrorism victims to sue the government of Saudi Arabia.

Why? The Middle Eastern country has been accused of helping 1 the terrorist group that conducted the September 11th, 2001 attacks. Fifteen of the terrorists were from Saudi Arabia. The Saudi government has denied having any role in the attacks.

Why did President Obama oppose the bill? He said it would interfere 2 with his ability to conduct foreign policy and that it could potentially lead to the U.S. government being sued in other country's court systems.

For its part, Saudi Arabia threatened to abandon hundreds of billions of dollars of investments in American assets if the bill passed.

Why did U.S. lawmakers support the bill? They felt the families of 9/11 victims deserve to have their day in court against Saudi Arabia. One attorney in the suit suggested that if the Saudi government was innocent, it wouldn't have to be afraid of the lawsuits 3.

So, what happened with the bill? President Obama vetoed it last week. But yesterday afternoon, Congress overrode 4 that veto. It was the first time that's happened since President Obama took office. Overriding 5 a veto takes a two-thirds vote in both the Senate and the House.

And it's pretty rare. Only around 4 percent of U.S. presidential vetoes had ever been overridden 6 according to "The Wall Street Journal".

The U.S. government is planning to send roughly 500 additional American troops to the Middle Eastern nation of Iraq. Right now, there are around 5,000 troops serving there. That includes those in Iraq on temporary status. The numbers have been increasing since 2014.

Iraq's government requested more U.S. forces to help out with the upcoming battle for Mosul, a city in northern Iraq that's controlled by the ISIS terrorist group. U.S. officials have indicated that the Americans might be closer to combat, though not at the front lines. That's significant because in 2014, President Obama said American combat troops would not be battling on foreign soil in the fight against ISIS.

U.S. officials expect this will be the last increase of American military troops in Iraq. But the nation will likely remain a challenge for America.

BEN WEDEMAN, CNN SENIOR INTERNATIONAL CORRESPONDENT: The next U.S. president will be caught between a rock and a hard place.

Barack Obama called U.S. troops out in his first term. Now, they're back. They're there to help crush ISIS, which was born in Iraq.

But the war against the terror group has obscured one important fact — Iraq is never far from falling apart.

There are three main groups in the country, the Kurds, who basically controlled much of the north, the Shia who ruled from Baghdad and are influenced by Iran, and the once dominance Sunni-Arab minority who don't trust the Kurds or the Shia.

In the post-ISIS future, the next American president will have the unenviable tasks of trying to keep Iraq together while at the same time preventing a return of ISIS in different incarnation.

It's not mission impossible, but it's close to it.