While the global economy will dominate at this weekend's summit of the Group of 20 industrialized and emerging-market nations, politics and security issues form the backdrop to the gathering of world leaders in the eastern Chinese city of Hangzhou.

Terror attacks in Europe, the looming U.S. presidential election and bloody ongoing conflicts in Syria and Iraq are among the issues making the world an uncertain and unsettling place.

World leaders including President Barack Obama, his Chinese counterpart Xi Jinping and German Chancellor Angela Merkel are expected to take up such topics, either when gathering as a group on Sunday and Monday or during bilateral meetings held on the summit's fringes.

Russian President Vladimir Putin, whose country has grown closer to China following the imposition of Western economic sanctions, will be in attendance, along with Indian Prime Minister Narendra Modi, French Prime Minister Francois Hollande and new British Prime Minister Theresa May. May will face questions about Britain's decision to leave the European Union and its impact on the global economy amid rising economic nationalism.

Despite the wealth of controversial issues, China seems determined to deliver a non-confrontational, even uneventful summit, having endowed it with the middle-of-the-road theme of: "Toward an Innovative, Invigorated, Interconnected and Inclusive World Economy."

"Accounting for two-thirds of the world population and more than 80 percent of global economic output, G-20 nations deserve, and are expected, to play a bigger role in the managing the world economy," the official Xinhua News Agency said in a recent commentary. "The upcoming summit is undoubtedly a prime opportunity."

Climate change, human rights and the fight against the Islamic State group will also feature during the meetings, with Obama and Xi expected to offer an update on progress toward ratifying the Paris agreement on reducing greenhouse gas emissions. White House officials have said they hope the historic climate change pact could enter into force by the end of the year.

Turkish President Recep Tayyip Erdogan will be present at his first major multinational gathering since a failed summer coup added new tensions to an already complex relationship with the U.S. and its allies.

Though no breakthroughs are expected, the gathering offers a chance for leaders to discuss disagreements ranging from China's claim to Japanese-controlled islands in the East China Sea to NATO's concerns over Russia's seizure of Crimea and the war in eastern Ukraine.

The opportunity even for pro-forma contact between disputants such as China and Japan is significant and "no doubt this will be hailed and heralded as a reduction in tensions," said Dean Cheng, senior research fellow at the Heritage Foundation in Washington, D.C.

North Korea's nuclear and missile programs are an especially sharp regional concern. Pyongyang this week denounced a U.N. Security Council statement condemning its four latest ballistic missile launches, calling it "a hostile act" perpetrated by the United States and warning that it could precipitate America's "self-destruction."

The North launched a ballistic missile from a submarine Aug. 24, days after the U.S. and South Korea began their annual military exercises. A press statement approved Friday night by all 15 Security Council members, including Pyongyang's ally China, called the four launches in July and August "grave violations" of a ban on all ballistic missile activity.

While China remains politically stable under stern, one-party communist rule, east Asia faces challenges ranging from Thailand's military governance to the election of Philippine President Rodrigo Duterte, whose bloody anti-drug campaign has drawn criticism from human-rights activists.

Obama is also expected to make a pitch for the Trans-Pacific Partnership free-trade agreement, a massive multination deal that has stalled in the U.S. Congress amid fierce election-year opposition from both Democrats and Republicans.

Along with Washington's "pivot" to Asia that has boosted American military presence in the region, the TPP is a centerpiece of Obama's policy toward the continent and seen as a litmus test for U.S. leadership. Host China is not a party to the proposed agreement and regards the pivot as a hostile attempt to contain its regional influence through strengthened military alliances with American allies including Australia and the Philippines.

China's assertions of its territorial claims in the South China Sea will weigh on the proceedings. A Hague-based international arbitration panel in July ruled against its claims to sovereignty over virtually the entire strategic water body. Beijing angrily rejected the verdict, vowed to continue developing man-made islands in the disputed area and says it would consider declaring an air defense zone that would require aircraft to heed its orders — a move sure to be condemned by the U.S., Japan and others.

As part of its efforts to counter such concerns, China has been pressing its drive for expanded economic cooperation through its "one-belt, one-road" policy linking it to Central and Southeast Asia and the Beijing-backed Asian Infrastructure Investment Bank.

Observers of the G-20 will be judging the response to such initiatives, whether "positive, reticent or divided," said University of Virginia China scholar Brantly Womack.

Leaders in attendance will also be considering the possible outcomes in November's U.S. elections, in which Democrat Hillary Clinton appears to have an edge over her Republican rival, Donald Trump. A former senator and secretary of state, Clinton is seen as an experienced hand on the wheel, while Trump has proposed policies that call into question America's commitment to free trade, immigration and the defense of its treaty allies.

While further from the core issues, ongoing conflicts in the Middle East and the wave of outward migration they've sparked also feature among concerns. Egypt's President Abdel-Fattah el-Sissi is among the specially invited guests at the meeting, likely bringing new scrutiny to his country's flailing economy and deepening security crisis.

The G-20 includes Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United Kingdom, the United States and the European Union.