Ties between China and the United States will be tested this year by many issues: currency, trade, Internet censorship, human rights, U.S. arms sales to Taiwan and President Barack Obama's meeting on Thursday with the Dalai Lama.

Leaders will also have several chances to meet, both at the bilateral level and at summits. Here is a timeline of significant dates this year:

January 12 - Google threatens to pull out of China over censorship and hacking attacks from within the country.

January 21 - U.S. Secretary of State Hillary Clinton delivers speech calling for Internet freedoms, names China as a country that has stepped up censorship of the web.

January 29 - Obama administration notifies U.S. Congress of proposed arms sales to Taiwan totaling $6.4 billion. Congress has 30 calendar days to review the proposal before the administration may conclude any deals.

February 17 - U.S. aircraft carrier USS Nimitz visits Hong Kong, the self-administered territory under Chinese rule, despite a Chinese pledge to suspend military exchanges with the United States after its announced arms sales to Taiwan.

February 18 - U.S. President Barack Obama scheduled to meet exiled Tibetan Buddhist leader, the Dalai Lama, at the White House. China reviles the Dalai Lama as a separatist for advocating self-rule for his homeland.

February 28 - Obama administration free to proceed with the weapons sales to Taiwan unless Congress passes legislation barring or modifying a proposed sale, something it has never done. Delivery of the weapons may take years.

February - U.S. State Department due to hold meeting with U.S. Internet firms about online freedom, a meeting that may dwell on policy toward China.

February-March - China, U.S. and other members of the United Nations Security Council likely to discuss proposed resolution putting additional sanctions on Iran over its nuclear activities.

March 5 - China opens annual parliamentary session, the National People's Congress. Usually at a news conference a day before the Congress opens, China announces its official defense budget for the year. The Communist Party-controlled parliament usually meets for about 10 days. At the end, Premier Wen Jiabao will give a high-profile news conference, giving him a chance to comment on U.S. ties and Taiwan.

April 12-13 - President Obama hosts an international nuclear security summit in Washington, D.C. Chinese President Hu Jintao would be his nation's most fitting representative at the meeting, but Beijing has yet to say whether he will go.

April 15 - U.S. Treasury due to release latest six-monthly report on whether China and other countries are manipulating their currencies for trade advantage.

May 15-25 - U.S. Secretary of Commerce Gary Locke leads trade mission to Hong Kong, China and Indonesia, promoting deals with American companies in clean energy.

Mid-year onwards - Senior officials from the United States and China will at some time gather in Beijing for Strategic and Economic Dialogue, an annual meeting to discuss key economic, foreign policy and security concerns.

June 26-27 - Meeting of G20 leaders of major rich and developing economies scheduled in Toronto, Canada, giving Presidents Hu and Obama an opportunity to meet.

Later in the year - The two countries are preparing for their Joint Commission on Commerce and Trade, a regular meeting that focuses on economic ties. Last year's was held in late October in the eastern Chinese city of Hangzhou.

November 2 - Mid-term elections for U.S. Congress. With economic concerns uppermost in many voters' minds, trade and currency tensions with China may become a electoral issue.

November 13-14 - Asia-Pacific Economic Cooperation summit, to be held in Yokohama, Japan, presents another opportunity for the two leaders to meet.

November - South Korea scheduled to host second summit for the year of the G20 group of major rich and developing economies, where Hu and Obama will have a further chance to meet. The summit is likely to take place immediately before or after the APEC summit.

November-December - When President Obama visited China in November 2009, Chinese President Hu accepted his invitation to visit the United States in 2010. No date has been set for Hu's trip, but it appears unlikely before the U.S. Congress mid-term elections.

For all its coolness toward Washington now, China would regard that visit as a big diplomatic trophy, and that may help to ease tensions beforehand.

December - Local elections for mayors and magistrates across Taiwan, the self-ruled island that China says belongs to it. No firm date has been set for the elections, which will cover about 60 percent of the island's electorate.

The vote will pit the more pro-China ruling Nationalist Party (KMT) against the independence-leaning opposition Democratic Progressive Party, and Beijing's policies toward Taiwan could be a major issue.

(Reporting by Chris Buckley in Beijing; Jim Wolf, Doug Palmer and Paul Eckert in Washington; Ralph Jennings in Taipei; Editing by Cynthia Osterman)

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