NEW DELHI – In just one decade, the United States has intervened militarily in three Muslim-majority countries and overthrown their governments. Now the same coalition of American liberal interventionists and neoconservatives that promoted those wars is pushing for punitive airstrikes in Syria without reflecting on how US policy has ended up strengthening Islamists and fostering anti-Americanism. Indeed, the last "humanitarian intervention” has clearly backfired, turning Libya into a breeding ground for transnational militants. As the intense US debate about President Barack Obama’s proposed use of military force highlights, the attack-Syria push is not about upholding America’s national interest. Rather, the desire to protect US "credibility” has become the last refuge of those seeking yet another war in the wider Middle East.If "credibility” was purged from the debate and the focus placed squarely on advancing long-term US interests, it would become apparent that an attack on Syria might not yield even temporary geopolitical gains. Beyond the short term, it would unleash major unintended consequences, potentially including an Iraq-style "soft” partition of Syria and the creation of a haven for extremists stretching across much of Islamist-controlled northern Syria and into the Sunni areas of Iraq.  Indeed, an attack would most likely increase America’s reliance on unsavory Islamist rulers in countries ranging from Saudi Arabia and Qatar to Turkey and the United Arab Emirates. Some Arab monarchs have pledged to bankroll the US attack – an investment that they would easily recover, given that the war talk has already increased oil prices. Al Qaeda-type groups already have gained ground in the Middle East and North Africa as an unintended byproduct of US policies, creating fertile conditions for stepped-up international terrorism in the coming years. The US invasion and occupation of Iraq, for example, created a major opening for Al Qaeda, whose affiliates now represent the Sunni struggle against the Shia-dominated government.Likewise, regime change in Libya aided the rise of Al Qaeda-linked militants, leading to the killing in Benghazi of the US ambassador. A system based on sharia (Islamic law) has been imposed, human-rights abuses are legion, and cross-border movement of weapons and militants has undermined the security of Libya’s neighbors.Meanwhile, America’s support for the regimes in Yemen and Saudi Arabia has contributed to the rise of Al Qaeda in the Arabian Peninsula. In parts of southern Yemen, an Al Qaeda affiliate, Ansar al-Sharia, functions as a de facto government. In Syria, where sizable chunks of territory are already under Islamist control and the pro-Al Qaeda Al Nusra Front overshadows the US-backed Free Syrian Army, the Obama administration is staring at the bitter harvest of its previous policy choices. Airstrikes now would merely make matters worse by undercutting the FSA’s grassroots legitimacy and aiding Islamist forces.Farther east, the US wants an "honorable” exit from Afghanistan – the longest war in its history – through a peace deal with the Taliban, its main battlefield opponent. In seeking to co-opt the Taliban – an effort that has resulted in the Taliban establishing what amounts to a diplomatic mission in Doha, Qatar – the US is bestowing legitimacy on a thuggish militia that enforces medieval practices in the areas under its control. America’s dalliances with Islamist-leaning political forces – and governments – have been guided by the notion that the cloak of Islam helps to protect the credibility of leaders who might otherwise be seen as foreign puppets. That simply will not work, even in the short term. On the contrary, until the Egyptian army removed him from the presidency, the Muslim Brotherhood’s Mohamed Morsi was coming to be seen by many as America’s man in Cairo.In the long term, the US will gain nothing – and risk much – by continuing to back oil sheikhdoms that fund Muslim extremist groups and madrasas from the Philippines and India to South Africa and Venezuela. By supporting Islamist rulers, the US is contributing to a trend evident from the Maghreb to the badlands of Afghanistan and Pakistan – Muslims killing Muslims.American policy has also contributed to a growing conflict between Islamist and secular forces in Muslim countries. This is best illustrated by Turkey, where Obama has ignored Prime Minister Recep Tayyip Erdoğan’s heavy-handed efforts to annul free speech and turn himself into a twenty-first-century Sultan.There and elsewhere, the US, motivated by the larger geopolitical goal of containing Shia Iran and its regional allies, has embraced Sunni rulers steeped in religious and political bigotry, even though they pose a transnational threat to the values of freedom and secularism. Moreover, the clash within Islam is likely to be destabilizing regionally and counterproductive to the interests of the free world. Against this background, Obama should heed the doctrine proposed in 1991 by General Colin Powell. The Powell doctrine stipulates that the US should use military force only when a vital national-security interest is at stake; the strategic objective is clear and attainable; the benefits are likely to outweigh the costs; adverse consequences can be limited; broad international and domestic support has been obtained; and a plausible exit strategy is in place.Given the US record since the doctrine was formulated, another criterion should be added: the main beneficiaries of military intervention are not America’s mortal enemies.Brahma Chellaney, Professor of Strategic Studies at the New Delhi-based Center for Policy Research, is the author of ‘Asian Juggernaut, Water: Asia’s New Battleground, and Water, Peace, and War: Confronting the Global Water Crisis.Copyright: Project Syndicate