Rescuers evacuate the injured outside of the Bataclan Theater in Paris after attacks launched by terrorists on the evening of November 13 (XINHUA/AP)

Terrorism remains rampant around the world. Throughout 2015, the world has been shocked by a number of deadly terror attacks that took place in the Middle East, Africa, Europe, and the United States, such as the January terror attacks of the Charlie Hebdo  satirical weekly magazine in Paris, the series of fatal attacks in Paris on the evening of November 13, and the December 2 brutal shooting at the Inland Regional Center in California. Radical militant groups including Nigeria's Boko Haram and Somalia's Al-Shabab continue to conduct horrible slaughters and abductions in many parts of Africa.

The surge of jihadists who join terrorist groups in war-torn countries like Iraq and Syria is a major factor threatening the global security, as extremist groups avenge their "enemies."

Now the so-called "Islamic State" (ISIS) has become the most prominent threat to international security, in parts because of its ability to carry out attacks beyond its center of power. The U.S.-led coalition and Russia have both launched air strikes campaign in Syria and Iraq against ISIS, but the two groups have different purposes in this fight as the control of Syria is at stake. The international community must still reach consensus on how to best eliminate terrorism and start to remove its root causes.

Russian and Syrian government forces bomb a place near Damascus controlled by opposition parties on December 13 (CFP)

The conflict in Syria will soon enter its sixth year of deadly fighting, which has become a battleground for geopolitical interests ranging from those of world leaders to armed militias.

The West holds the position that Bashar Assad must relinquish power, while Russia insists that Assad's regime remains the only legal authority in Syria to implement state functions.

On September 30, Russia launched a bombing campaign in Syria, saying it was targeted at ISIS terrorists. A series of chain reactions have been triggered ever since. A Russian passenger plane carrying 224 people was brought down in Egypt's Sinai Peninsula on October 31, reportedly by ISIS. A Russian fighter jet was shot down on November 24 by Turkish forces which claimed the jet was within the Turkish border.

Unfortunately, any solution to Syria crisis remains uncertain, and the violence is only escalating at the price of innocent civilians.

This year marked the 70th anniversary of the end of World War II (WWII), with almost every country commemorating in its own way.

WWII was the most widespread and deadliest war in history, involving more than 40 countries, 70 million soldiers and resulting in estimated 50 to 80 million deaths.

International leaders repeated calls to learn from history and also called for the peaceful development of the world moving forward.

A comprehensive accord on Iran's nuclear issue was reached in Vienna on July 14 between the five permanent members of the UN Security Council plus Germany and Iran. Based on the Joint Comprehensive Plan of Action, Iran agreed to limit its nuclear activities in return for the lift of crippling sanctions. On July 20, the nuclear deal was approved by the UN Security Council, signifying that the 10-year-long international sanctions imposed by the UN against Iran are likely to be removed if Iran complies with the agreement.

The comprehensive accord is a milestone of international efforts to solve Iran's nuclear issue. Iran's right for the peaceful use of nuclear energy is guaranteed in the deal, while its nuclear program will be monitored by international inspectors. With sanctions lifted, Iran will be able to improve its domestic economy and people's livelihoods through international trade and cooperation. Furthermore, the deal opens a new chapter for Iran and the West to improve their strained relations, which could have an impact on Iran's relations with Israel, the Arab world, as well as on the situation in the Middle East.

Migrants and refugees stand in line as they wait to board a train at a registration camp after crossing the Macedonian Greek border near Gevgelija on September 28 (CFP)

Throughout 2015, millions of refugees from the Middle East and Africa have streamed into Europe through land and maritime routes. Poverty and war are the major factors causing the continuous refugee surge, especially the war in Syria.

The influx of refugees has brought an unprecedented humanitarian crisis to many European countries, while accidents and casualties of refugees during their journeys are both frequent and horrifying.

The migrant crisis has also become a political test for the European Union. After a number of consultations and severe disagreements between member states, the EU has established interim mechanisms to deal with the migrant challenge. The newly elected Prime Minister of Canada, Justin Trudeau, promised to accelerate Canada's commitment to taking in Syrian refugees, with many international organizations calling on others to do the same.

Trade ministers of 12 countries in the TPP talks hold a joint press conference to announce the end of negotiations in Atlanta, the United States, on October 5 (XINHUA)

Delegates from governments of 12 countries in the Asia-Pacific region announced on October 4 that the multi-year negotiations of the Trans-Pacific Partnership Agreement (TPP) had reached consensus after the last round of talks held in Atlanta, Georgia. The agreement must still be approved by the participating countries' legislatures.

U.S. President Barack Obama attached great importance to the TPP, a "high-standard" free trade agreement led by the United States. The TPP will have an influential impact on current global trade rules and other ongoing regional free trade agreements. The World Trade Organization is the most representative international body for making world trade rules, but its position has been weakened since the Doha round trade talks have been perpetually stuck. The United States is also in negotiations of the Transatlantic Trade and Investment Partnership (TTIP) with the European Union.

Greek citizens protest against the austerity measures which were approved by the Greek Parliament on June 30 (XINHUA/REUTERS)

Like in recent years, the prolonged debt burden of Greece constantly sounded the red alarm for the eurozone in 2015. On June 30, Greece became the first developed economy that failed to repay loans to the International Monetary Fund. Eurozone leaders urged Greece to adopt reform and austerity measures in return for new bailout. But Greek Prime Minister Alexis Tsipras wanted to loosen austerity policy and Greek citizens wanted their country's debts to be written off. The country even threatened to quit the eurozone.

After marathon talks in Brussels, however, eurozone leaders reached an agreement for a third Greek bailout. On August 11, the Greek Government conditionally agreed to receive up to 86 billion euro ($95 billion) over three years, which remits Greece's debt woes and saves the unity and integrity of the eurozone. In concession, Greece must make economic reforms on taxation, pensions, the labor markets, banks and privatization. The new deal led to a drop in domestic support for Tsipras. To safeguard the bailout, Tsipras announced his resignation on August 20, but was reelected as prime minister in a snap election in September.

Japan’s opposition parties try to stop the special committee from passing the new security bills in the Diet on September 17 (XINHUA)

Japan took further steps to lift restricts of its pacifist constitution on national defense policy. Japanese Prime Minister Shinzo Abe and his ruling coalition approved new security bills in the lower house of parliament on July 16. Despite strong opposition and large-scale protests, Japan's upper house passed the measure on September 17.

With the new law, Japan is pivoting its national defense toward proactive participation in regional and world affairs. The new bill on "military aid for international peace" permits the Japanese Government to send troops and arms overseas without any restriction. Opposition called the security bills war legislation, saying the move ignores the tragic historical lessons of Japan's military expansion, blatantly thwarts the Japanese constitution, and belittles the public commitment to pacifism.

Japan's move has also sparked concern from neighboring countries, including China and South Korea, which have historical and territorial disputes with Japan.

A helicopter view of the Yacheng 13-1 deep-water drilling platform of China in the South China Sea (XINHUA)

Territorial disputes over islands and reefs in the South China Sea grew increasingly complicated as the United States and Japan in 2015 used "the freedom of navigation" to explain their interests in the South China Sea. Representatives of the two countries have also spoken of China as a "threat" in the region while speaking at international platforms.

In addition to diplomatic rows, the United States strengthened their patrol and surveillance activities in the South China Sea. U.S.S. Lassen's entry into waters near relevant islands and reefs of China's Nansha Islands in late October triggered a wave of protest. The Chinese saw the move of the U.S. battleship as provocative. But all sides exercised restraint when dealing with one another.

French Foreign Affairs Minister and president of the Paris climate change conference Laurent Fabius announces the adoption of a historic global warming pact on December 12 (CFP)

The UN Sustainable Development Summit 2015, held from September 25-27 in New York City, was significant in its adoption of the ambitious post-2015 development agenda.

A plan of action, the 2030 Agenda for Sustainable Development, was approved by 193 UN member states at the assembly. The 2030 agenda outlines 17 sustainable development goals with 169 associated targets which are integrated and indivisible. It is the most broad and universal policy agenda that world leaders have ever pledged.

This year also marked the deadline for fulfillment of the Millennium Development Goals (MDGs) that the UN had set in 2000. Over the past 15 years, the achievement under the MDGs have helped people all over the world remove the shackles of poverty and hunger, most significantly in China, which has lifted hundreds of millions of citizens out of poverty. But the world still has a large gap to fill. In the face of serious global challenges, the international community must make concerted efforts to reach the development goals as soon as possible and "end poverty in all its forms."

A landmark agreement on climate change was signed by 196 parties of the UN Framework Convention on Climate Change at the 21st session of the Conference of the Parties hosted in Paris on December 12. The deal aims to hold global average temperature rises to no more than 2 degrees centigrade above pre-industrial levels. It is the first global agreement on climate change, a crucial point in the global climate governance process.