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In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
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We're not bluffing, the Obama administration told Afghanistan on Tuesday in announcing for the first time it has started planning for the possible withdrawal of all U.S. troops by the end of the year if no security agreement is signed. Statements by the White House and Defense Secretary Chuck Hagel showed President Barack Obama's impatience with Afghanistan President Hamid Karzai's refusal to sign the agreement that would keep several thousand American troops in the country after combat operations conclude this year. In a phone call with Karzai on Tuesday to discuss upcoming elections for a new Afghan leader, Obama made clear that time was running out to properly plan for keeping any U.S. forces in the country beyond 2014, the White House said.President Obama calls Afghan leader to discuss security agreementObama orders planning for bringing home all U.S. troops at the end of 2014Afghan President Karzai refuses to sign a deal to keep some troops thereThe White House says an agreement could happen after Karzai leaves office in April 
 Question:Obama, he said, has been very clear that the possibility of U.S. troops staying in Afghanistan depends "on whether we have a bilateral security agreement signed by the Afghani government, to assure our rights of our troops and other important elements that are required any time _ has troops in another country."
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U.S.


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Washington (CNN) If Donald Trump's campaign aides like Paul Manafort were contacting Russian officials during the campaign, then the President had nothing to do with it, claims former Trump campaign manager Corey Lewandowski. "If anybody crossed a line and gave information to a foreign agent or foreign government or foreign intelligence official, whether that's Paul Manafort or it's Rick Gates or anybody else, I hope they're held accountable," Lewandowski told David Axelrod on "The Axe Files," a podcast from the University of Chicago Institute of Politics and CNN. He later added: "Any staffer who contacted or potentially contacted a Russian agent or a Russian official has done so on their own accord and not at the direction of the campaign, the President or anybody else in the administration."Lewandowski attempted to shield the PresidentManafort has denied the alleged contact as "100% not true" 
 Question:Lewandowski and _ were considered part of two rival power centers in the campaign during the time they overlapped.
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Paul Manafort


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London (CNN) Tensions over Europe's migrant crisis led to arrests and violence in Sweden and the UK over the weekend, with a masked mob calling for attacks on foreigners in Stockholm and clashes between pro- and anti-migrant demonstrators in the British town of Dover. In Sweden, nearly 100 men gathered Friday night in the capital, handing out leaflets calling for attacks on migrants, Stockholm police spokesman Albin Naverberg told CNN. Some of the men were wearing black clothes and masks, he said. Reports of attacks on people from immigrant backgrounds surfaced in Swedish media and on social media, but police said they had received no reports of assaults on civilians.Mob hands out leaflets in Stockholm calling for assaults on migrants, police sayIn UK, pro- and anti-migrant protesters clash in DoverTensions rise as Europe faces largest migrant crisis in decades 
 Question:Friday's tensions were the latest in a series of incidents involving migrants in _.
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Sweden