President Obama arrives for a United Nations Peacekeeping Summit on Monday at United Nations headquarters in New York. (Andrew Harnik/AP)

Since the first modest force of United Nations blue helmets was deployed to maintain an Arab-Israeli cease-fire in 1948, millions of troops from around the world have participated in U.N. peacekeeping operations. They have kept Greeks and Turks apart, separated Pakistanis and Indians, and monitored the cessation of hostilities between Ethiopia and Eritrea.

But the difficulties that U.N. peacekeepers face have changed substantially in recent years, and the force is showing its age.

“Old challenges persist,” President Obama said Monday at a high-level meeting, convened by the United States, on the future of peacekeeping. “Too few nations bear a disproportionate burden of providing troops, which is unsustainable. Atop this, we’ve seen new challenges — more armed conflicts, more instability driven by terrorism and violent extremism, and more refugees.”

Today, a handful of mostly developing countries — led by Bangladesh and Ethi­o­pia — provide the majority of more than 100,000 troops and police devoted to 16 peacekeeping operations around the world. Often badly equipped and poorly trained, the forces are ill prepared to face conflicts in places such as South Sudan, where neither side seems interested in peace, and Mali, where troops have little defense against ongoing and asymmetrical warfare in the desert.

Russia’s president blamed foreign intervention in North Africa and the Middle East for creating a terrorist-fueled “anarchy.” (Reuters)

In response to Obama’s summons, heads of government attending this year’s U.N. General Assembly filed to the microphone to pledge to do more. China, in keeping with its desire to play a larger role on the world stage, pledged an additional 8,000 people for a new peacekeeping standby force, training for 2,000 peacekeepers from other countries and $100 million for African Union stabilization forces.

Obama left the session after about an hour and a half, for an appointment with Russian President Vladimir Putin. But the procession of promises, from about 50 nations in all, went on in his absence, for total pledges of about 40,000 additional troops and police.

Rwanda, which became a lasting symbol of U.N. failure when an estimated 1 million civilians were killed in internecine warfare in 1994 — while a token force of fewer than 300 international peacekeepers stood by powerless — said it would contribute two infantry battalions and a female police unit.

Colombia, which is seeking a new role for its armed forces as it heads toward a peace agreement ending its decades-long guerrilla war, said it would significantly increase its commitment as soon as the accord is solidified.

Europe, which has largely dropped out of the peacekeeping business in recent years, was represented by several leaders. British Prime Minister David Cameron said his country would send hundreds of troops to Sudan and Somalia as trainers. Others pledged equipment and contributions to the peacekeeping budget, currently $8.3 billion, of which the United States pays 28 percent.

“We know that peace operations are not the solution to every problem,” Obama said, “but they do remain one of the world’s most important tools to address armed conflict.”

Although it pays more than any other country for peacekeeping, the United States is among the smallest contributors of troops, with 42 police, six military experts and 34 troops. In a presidential directive issued just before the summit meeting, Obama said he would double the number of military officers and significantly increase other contributions.

“We will offer logistical support, including our unrivaled network of air- and sea-lift. When there’s an urgent need and we’re uniquely positioned to help, we’ll undertake engineering projects like building airfields and base camps for new missions,” he said. “And we’ll step up our efforts to help build the U.N.’s capacity, from identifying state-of-the-art technology to offering training to protection against IEDs,” or improvised explosive devices.

The push to improve peacekeeping began last year, when Vice President Biden convened a similar summit at the General Assembly. The last major changes in U.N. operations, expanding rules for protection of civilians, came two decades ago, after Rwanda and the 1995 genocide against Muslim civilians in Bosnia.

U.N. Secretary General Ban Ki-moon last year appointed an independent panel to examine the peacekeeping operation and recommend changes. During the summer, the military commanders of three of the most challenging missions briefed the Security Council on some of their problems.

The head of the U.N. mission in South Sudan spoke of the difficulty of protecting civilians without required “logistical, financial and human resources that fit the mandate, expectations and realities on the ground,” including close air support, intelligence and medical evacuation capability.

Irish Maj. Gen. Michael Finn, commanding the U.N. Truce Supervision Organization between Syria and Israel over the Golan Heights, said that restrictions imposed by many contributing countries on their troops to avoid risks in a conflict zone had made his job even more difficult.

The commander of U.N. forces in Mali, Maj. Gen. Michael Lollesgaard of Denmark, spoke of the need for “the capability to face hostile armed groups hiding among the population and to face challenging climates, geography and infrastructure.”