“At this summit, more than 50 countries from Bangladesh to Colombia to Finland and China are making commitments totaling more than 30,000 new troops and police”, Obama told a peacekeeping summit held on the sidelines of the UN General Assembly.

But the difficulties that United Nations peacekeepers face have changed substantially in recent years, and the force is showing its age. “Too few nations bear a disproportionate burden of providing troops, which is unsustainable”.

For months, officials such as the US military’s top officer and U.S. Ambassador Samantha Power have pressed countries, especially European ones, to contribute more.

Obama left the session after about an hour-and-a-half for an appointment with Russian President Vladimir Putin.

Monday’s pledges of new troops and police significantly exceed the 10,000 goal that USA officials had mentioned.

Europe, which has largely dropped out of the peacekeeping business in recent years, was represented by several leaders.

British Prime Minister David Cameron announced 70 troops for the UN-African Union mission in Somalia and up to 300 troops for the United Nations mission in South Sudan, which is grappling with one of the world’s worst humanitarian crises. Others pledged equipment and contributions to the peacekeeping budget, now $8.3 billion, of which the United States pays 28 percent.

“The United States has compelling reasons to support the effective conduct of U.N. and other multilateral peace operations, but must be judicious about where we advocate their establishment since they are not the appropriate response in all instances”, the president said in his memo, noting that U.N. peace operations ordinarily are not designed and equipped to deploy into situations of active armed conflict where the main protagonists and their external backers are not yet ready to stop fighting.

“Their numbers are now rising globally, and may continue to do so over the next decade or more”, the president said in the memo.

– Leading and supporting efforts at the United Nations for systemic reform. “Unless we work with other nations under the mantle of global norms and principles and law that offer legitimacy to our efforts, we will not succeed”. “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. Elsewhere, like the Democratic Republic of the Congo, peacekeepers are countering violent armed militias; in Mali they are confronting the proliferation of improvised explosive devices.

He assured that if the steps that he had announced were embraced, then it would strengthen the peace operations for the decades to come.

“Mr Secretary General, we commend you for raising this issue”. During the summer, the military commanders of three of the most challenging current missions briefed the Security Council on some of their problems.