MANILA, Philippines — Southeast Asia started banding its unwieldy cluster of fledgling democracies, monarchies and authoritarian regimes into an EU-like collective half a century ago, but the diverse region of 620 million people remains hampered by conflicts, poverty, human rights crises and other issues.

It has nevertheless evolved into an important arena of discourse, power plays and influence that gathers world leaders in annual summits.

Leaders of the Association of Southeast Asian Nations will mark the 10-nation bloc’s 50th anniversary with handshakes, unity photo-ops and pageantry in a gala dinner on Sunday. They’ll gather for two days of summitry under tight security in Manila starting Monday and meet world leaders led by President Donald Trump to tackle a slew of security worries.

A list of the most pressing issues:

NORTH KOREA

Manila is the last stop on Trump’s Asian swing where he’s expected to lobby for more punitive action, including diplomatic sanctions, against Pyongyang over its nuclear program. He’ll generally find a receptive audience, with the summit’s foul-mouthed host, President Rodrigo Duterte, having called North Korea’s leader a “crazy son of a bitch” with a “chubby face that looks kind” but who could wipe the region off the map with his “dangerous toys.”

China, which wields considerable influence on ASEAN, will, however, be a tempering presence. It has called for dialogue with North Korea and urged the United States to tone down its rhetoric, arguing that sanctions alone cannot solve the impasse.

ASEAN leaders will likely stick to their expression of alarm over Pyongyang’s ballistic missile and nuclear tests and press their call for North Korea to return to long-stalled denuclearization talks.


MUSLIM MILITANTS

The siege by pro-Islamic State group militants that left at least 1,172 combatants and civilians dead and left swaths of the southern Philippine city of Marawi in smoldering rubbles will be on every leader’s mind in Manila.

Although Philippine troops have essentially crushed the five-month insurrection, the massive militant attack served as a reality check for governments of the new scale of havoc IS-aligned militants could wreak on urban areas.

Consequently, the main summit venue in a theater complex by Manila Bay has been placed in a security lockdown and declared a no-fly and no-sail zone. Nearly 60,000 police and military personnel will keep watch in Manila and Clark Freeport to the north where some of the leaders will land and senior diplomats are meeting.

Duterte plans to brief leaders on how Filipino forces quelled the siege. ASEAN states and their Asian and Western counterparts find a common interest in addressing the resurgent threat of terrorism and radicalization without much friction.


ROHINGYA DILEMMA

Alarm over violence in Myanmar’s western Rakhine state that has forced more than 600,000 Rohingya Muslims to flee to Bangladesh will likely stay off ASEAN’s formal agenda and summit communique. That’s because its member states, which include Myanmar, uphold a bedrock policy of non-interference in each other’s domestic affairs.

While the policy has held back the regional group from taking a stronger and more relevant stance on such calamities in step with much of the international community, it has allowed ASEAN to endure as a club of nations with disparate backgrounds.

Individually, however, heads of state can raise concern and outrage over the Rohingya crisis during their so-called “retreat,” a free-for-all but closed-door session. Malaysia, among others, is expected to push Myanmar to take stronger steps to address the humanitarian problem, which has caused many of the Rohingya to flee to its territory. Malaysia has also pushed the Philippine host to allow a stronger statement on the crisis, causing some tension.

“If it will be discussed, it will be up to Myanmar to raise the issue because this a domestic concern for them,” said Robespierre Bolivar, spokesman of Manila’s Department of Foreign Affairs.


SOUTH CHINA SEA

The leaders of China and ASEAN, which includes four member states directly involved in South China Sea territorial disputes, are expected to announce the start of negotiations on a so-called “code of conduct” in the contested waters based on a framework or outline that their foreign ministers endorsed in August.

Both sides would laud such progress, which China acquiesced to after the Philippines under Duterte backed down from being one of Beijing’s most virulent U.S.-backed critics. Duterte pursued a policy of rapprochement with Beijing and has not immediately pushed for Chinese compliance with an arbitration ruling by a U.N.-aligned tribunal that invalidated China’s expansive claims in the strategic waterway.

“There is more cooperative spirit in managing, in reducing the tensions there,” Bolivar said.

ASEAN, however, has been dismissed as an ineffective broker largely because it tends to get paralyzed by indecision due to its consensual decision-making style when many of its member states are either aligned with China or the U.S. The two-page framework took 15 years to conclude and lacked key provisions, including a dispute-settlement mechanism, that China opposes.

“The biggest problem is our insistence that, for some reason, ASEAN has to solve this, which it’s not equipped to do, and we shouldn’t force it to,” said Greg Poling, a Washington-based South China Sea expert.