NEW YORK - US President Barack Obama, in his final address to UN General Assembly on Tuesday, insisted that diplomacy was the only way to end the brutal five-year conflict in Syria, as a ceasefire brokered by Washington and Moscow lay in tatters.

"There's no ultimate military victory to be won, we're going to have to pursue the hard work of the diplomacy that aims to stop the violence and deliver aid to those in need," Obama told the United Nations.

Obama's longstanding differences with Russian President Vladimir Putin over his actions in Ukraine have accompanied intense disagreement over Syria's future and a series of failed attempts by Russia and the US to resolve the civil war there together.

"In a world that left the age of empire behind, we see Russia attempting to recover lost glory through force," Obama said.

Unleashing his criticism of Russia, Obama said: “ If Russia continued to interfere in the affairs of its neighbors, it may be popular at home. It may fuel nationalist fervor for a time. But over time, it's also going to diminish its stature and make its borders less secure. In the South China Sea, a peaceful resolution of disputes offered by law will mean far greater stability than the militarization of a few rocks and reefs and added “We are all stakeholders in this international system. And it calls upon all of us to invest in the success of institutions to which we belong”.

“Consider what we've accomplished here over the past few years. Together, we mobilized some 50,000 additional troops for U.N. peacekeeping, making them nimble, better equipped, better prepared to deal with emergencies. Together, we established an open government partnership so that increasingly transparency empowers more and more people around the globe. And together, now, we have to open our hearts and do more to help refugees who are desperate for home”, Obama argued.

Obama also called for more global cooperation especially in helping refugees from war-torn countries – while making only passing reference to the Islamic State and the ever-expanding scourge of like-minded terror groups.

The president's focus on refugees comes after Obama was criticized by other nations for not doing enough to help those fleeing their countries because of war or for other reasons.

Last week, the White House announced that the U.S. would resettle 110,000 refugees in the coming year, a 30 percent increase over the 85,000 allowed in this year.

More than four dozen US businesses also pledged $650 million in support to help refugees, the White House announced Tuesday.

“We coordinated our response to avoid further catastrophe and return the global economy to growth,” Obama said.

In his eighth address to the UNGA, he said: “We've taken away terrorist safe havens, strengthened the nonproliferation regime, and resolved the Iranian nuclear issue through diplomacy. The US has closer relations with Cuba, helped Colombia end Latin America's longest war, and it welcomed a democratically elected leader of Myanmar to this assembly.”

The president called for a ‘course correction’ for globalisation to ensure nations don't retreat into a more sharply divided world, while pushing back against an isolationist approach gaining popularity in many countries. He advocated for open democracies and open economies, while railing against the example set by Russia and calling for more tolerance in all nations.

He also took what appeared to be a jab at Donald Trump, saying: “The world is too small for us to simply be able to build a wall” and prevent extremism from affecting societies.

With that message in hand, Obama urged nations to “follow through even when the politics are hard,” in helping refugees fleeing conflict.

“We have to open our hearts and do more to help refugees who are desperate for a home,” he said. “We have to have the empathy to see ourselves.”

Obama said Israel will be better off if it makes peace with Palestinians and realize it cannot permanently occupy the Palestinian lands.

"Surely Israelis and Palestinians will be better off if Palestinians reject incitement and recognize the legitimacy of Israel ... (and if) Israel recognizes that it cannot permanently occupy and settle Palestinian land," Obama told the 193-member Assembly in its packed hall.

Opening the Assembly's General Debate on Tuesday, UN Secretary-General Ban Ki-moon also addressed the Israeli-Palestinian issue. 

“As a friend of both the Israeli and Palestinian peoples, it pains me that this past decade has been ten years lost to peace,” Ban said.

“Ten years lost to illegal settlement expansion. Ten years lost to intra-Palestinian divide, growing polarization and hopelessness. This is madness," he said. 

The Obama administration recently strongly criticized Israel’s illegal settlement activities, saying they run counter to the advice provided by the Middle East Quartet, a group which includes the United Nations, European Union, Russia and the United States.

The presence and continued expansion of Israeli settlements in occupied Palestine has created a major obstacle for the efforts to establish peace in the Middle East region.

More than half a million Israelis live in over 230 illegal settlement colonies built since Israel’s occupation of the Palestinian territories of the West Bank and East Jerusalem al-Quds.