To kick off the debate, the 15-member council issued a statement, reaffirming its "commitment to the Charter of the UN, including the purposes and principles of the Charter, and an international order based on international law."
The council's presidential statement urged all member states to fully comply with the UN Charter and recognized the critical importance of the Charter to the maintenance of international peace and security.
Briefing the council, UN Secretary-General Antonio Guterres lamented that this year began with fresh turmoil and long-standing suffering and geopolitical tensions reached "dangerous levels," most recently in the Gulf.
He said the Security Council under the UN Charter has primary responsibility for the maintenance of international peace and security, and that the UN Charter remains the world's shared framework of international cooperation for the common good.
Recalling the content of the charter, the secretary-general called for peaceful settlement of disputes, equal rights of men and women, non-intervention, self-determination and sovereign equality of member states.
Guterres also pointed to the clear rules governing the use of force as set out in the charter.
In addition, he highlighted prevention of conflict and outlined many available tools in the charter, including negotiation, enquiry, mediation, conciliation, arbitration and judicial settlement.
Over 110 countries have signed up for the marathon debate that is set to last until Friday.
On Thursday morning, the debate was presided over by Vietnamese Deputy Prime Minister and Minister of Foreign Affairs Pham Binh Minh, whose country holds the rotating presidency of the Security Council for January.
In his national capacity, Pham said recent worrying events in the Middle East underscore the utmost importance of upholding the UN Charter.
"Recent worrying events in the Middle East ever more underscore the utmost importance of upholding the Charter, especially principles of non-use of force, respect for the sovereignty and territorial integrity of states, and peaceful settlement of disputes," said Pham.
"Disrespect for the Charter and international law, on the other hand, has been posing serious threats to international and regional peace and security and challenged the very relevance and legitimacy of the UN," he added.
"Respect for the UN Charter has been pivotal in preventing another world war, promoting peaceful solutions for conflicts all over the world, and maintaining international peace and security," He said.
Underlining emerging and complex global challenges, he noted the UN Charter proves to be more relevant and essential than ever. "We must act to ensure that the UN and its actions reflect the common interests of all member states. We must promote multilateralism and equitable relations amongst states in accordance with the UN Charter."
China's Permanent Representative to the UN Zhang Jun, for his part, reaffirmed China's commitment to upholding multilateralism as well as the purposes and principles of the UN Charter.
He said that as a cornerstone of multilateralism, the charter establishes the basic norms governing international relations in the present day, develops generally recognized principles of international law, and charts the way forward for human society.
Against this backdrop of emerging unilateralism, protectionism and acts of bullying, Zhang said "revisiting and reminding ourselves of the spirit of the charter is all the more relevant" as this year marks the 75th anniversary of the UN.
China's proposal of building a community of shared future for humankind is a continuation and sublimation of the purposes of the UN charter, Zhang said, affirming that China will honor its commitment, uphold the principle of peaceful settlement of disputes, and uphold sovereign equality, political independence and territorial integrity of all countries and non-interference in other countries' internal affairs, and the principle of no threat or use of force.
Thursday's debate coincided with rising tensions in the Gulf, as Iran on Tuesday fired more than a dozen missiles at bases used by U.S. military in Iraq in retaliation of the U.S. killing of Iranian commander Qassem Soleimani.
The United States denied an entry visa to Iran's Foreign Minister Mohammad Javad Zarif who was invited to speak at the debate, citing shortage of time to process his application.
In her speech, Mary Robinson, chair of The Elders, an independent group for peace, justice and human rights, lamented the U.S. visa denial to Zarif, a move that in effect prevented him from attending the meeting.
Robinson said Zarif "was going to speak about the role of the UN charter in supporting international peace and security, but is being prevented from doing so as tensions have arisen between Iran and the United States."
"This is highly regrettable. It is precisely in times such as these that we need to hear the voices of all concerned," said the former first woman president of Ireland.
Although Zarif was not able to speak to the council in person, his speech was delivered by Iran's Permanent Representative to the UN Majid Takht Ravanchi, who explicitly blasted the United States.
"The world is at a crossroads: with the end of monopolies on power, one unhinged regime is frantically clamoring to turn back time," he said. "This has meant more damaging American unilateralism in defiance of international norms and law, most recently a dastardly targeted assassination of the heroes who were the nightmare of groups such as ISIS."
Also in his speech, Zarif blasted what he called U.S. economic terrorism and said the U.S. has adopted "mob tactics to expand or gain market share" in the face of the increasing diversification of the sources of power.
"In the case of my own country, U.S. economic terrorism has involved the strangulation of access of ordinary Iranians to food and medicine as well as use of illegal unilateral sanctions to give American oil a foothold in Asia," said the foreign minister.
Zarif called for renewed commitment to the Charter, "particularly non-intervention in internal or external affairs and prohibition of the threat or use of force."
In defense of the recent U.S. action in the Middle East, U.S. Permanent Representative to the UN Kelly Craft claimed "for years, Iran and Iranian-supported militias in the region have threatened the lives of Americans and shown unyielding contempt for the authority of the UN."
She said her mission has submitted a letter to the Security Council, which detailed "an escalating series" of such Iranian attacks in recent months.