President Barack Obama declared yesterday that the US remains the world's most indispensable nation, even after a "long season of war", but argued for restraint before embarking on more military adventures.
Obama's speech signalled a concerted effort by the White House to push back against critics who contend that the president's approach to global problems has been too cautious and has emboldened adversaries in Syria, Russia and China.
In a wide-ranging speech on foreign policy to US military cadets at West Point, Obama said that the United States should shun isolationism and that its military must be prepared for crises. "Regional aggression that goes unchecked - whether it's southern Ukraine, or the South China Sea, or anywhere else in the world - will ultimately impact our allies, and could draw in our military," Obama said.
But he emphasised caution on any decision to use force and said: "American influence is always stronger when we lead by example.
"It's a lot harder to call on China to resolve its maritime disputes under the Law of the Sea Convention when the United States Senate has refused to ratify it - despite the repeated insistence of our top military leaders that the treaty advances our national security.
"That's not leadership; that's retreat. That's not strength; that's weakness," Obama said.
Senators of the rival Republican Party have refused to ratify the treaty, saying that the UN convention would override US sovereignty.
Even as the US emerges from the two wars that followed the September 11, 2001 attacks, Obama said terrorism remained the most direct threat to American security. But he argued that as the threat has shifted from a centralised al-Qaeda to an array of affiliates, the American response must change too.
Rather than launching large-scale military efforts, Obama called for partnering with countries where terrorist networks seek a foothold.
That effort includes a new US$5 billion fund to help countries fight terrorism and to expand funding for Defence Department intelligence, surveillance, reconnaissance, special operations and other activities.
Obama cast the bloody civil war in Syria as more of counterterrorism challenge than a humanitarian crisis. He defended his decision to keep the US military out of the conflict but said he would seek to increase support for the Syrian opposition, as well as neighbouring countries including Jordan, Lebanon, Turkey and Iraq that have faced an influx of refugees and fear the spread of terrorism.
"In helping those who fight for the right of all Syrians to choose their own future, we also push back against the growing number of extremists who find safe haven in the chaos," Obama said.
The president's speech came one day after he outlined plans to wind down America's lengthy war in Afghanistan by the end of 2016. The blueprint calls for keeping 9,800 troops in Afghanistan for training and counterterrorism even after combat missions end later this year, but then withdraw them within two years.
Obama also praised continuing diplomatic efforts between Iran, the US and its negotiating partners - Germany, Britain, France, China and Russia - that aim to strip the Islamic republic of its nuclear capabilities.
While Obama said the odds of reaching an agreement were still long, he also said a diplomatic breakthrough would be "more effective and durable than what would be achieved through the use of force".