That ambition and drive have been conspicuously in evidence of late. In a high-profile gambit involving mediation by Tony Blair, Britain’s former prime minister, Qatar helped force Glencore to increase its takeover bid last autumn for the miner Xstrata, in which Qatar’s sovereign wealth fund held a large stake, increasing the price of the multibillion-dollar deal 9 percent, said Jeff Largey, an analyst at Macquarie in London.

Despite being a tightly controlled monarchy, Qatar is the only Gulf country that has enthusiastically bought into the Arab Spring revolutionary movements that have roiled the Middle East over the past two years. Qatari aid was instrumental in toppling the Libyan dictator, Col. Muammar el-Qaddafi, and its leadership was early in calling for the departure of President Bashar al-Assad of Syria. Qatar has backed the government of President Mohamed Morsi of Egypt with promises of billions in investment, including money for an oil refinery near Cairo.

Some of these decisions, like investing in the Xstrata deal or Qatar’s supplying new capital to Britain’s Barclays bank during the financial crisis — a matter that is now under investigation in Britain — make good business sense. So does Qatar’s stake-building in major Western companies including Shell, the German construction giant Hochtief and Volkswagen. But they also help accentuate Qatar’s political clout. When buying large shareholdings “you are gaining access to a network. It’s almost a means of doing politics,” said a senior Western investment banker in the Gulf last year, who declined to be identified because it might affect his business.

Being the site of billions of dollars in investment by major oil companies including ExxonMobil, Shell and Total also enhances Qatar’s relevance, as do its L.N.G. contracts with countries like Japan and China. The Qataris are thinking “if you have many long-term partners around the world, you won’t be sacrificed in a time of need,” said Mr. Ulrichsen of Chatham House.

In this context, Al Jazeera’s plan to expand in the United States may be seen as another part of Qatar’s global outreach campaign, though Al Jazeera has changed its tactics from its early days.

Al Jazeera’s English channel, introduced in 2006, has helped at least partially change its image from that of a network used as a vehicle by Al Qaeda and hostile to the United States to that of a professionally run news channel that has won prominent U.S. journalism prizes, including George Foster Peabody and George Polk awards last year. The Polk prize came for coverage of unrest in Bahrain, another small Gulf emirate.

“The key question is whether this is to give Al Jazeera in English more exposure in its current relatively objective form or to buy a forum for sending more of a Qatari and Arab message to U.S. viewers,” said Anthony H. Cordesman, a Gulf security expert at the Center for Strategic and International Studies in Washington.

The English channel has struggled to find viewers in the United States. It reaches only 4.7 million homes and far fewer actual viewers. The deal for Current TV will multiply potential viewers almost tenfold. “This is intended to be a commercial venture,” said Stan Collender, a spokesman for the company. Al Jazeera made the purchase only after “several years of study,” he said.