WASHINGTON (AP) — After years of Republicans dominating the politics of national security, this year’s GOP presidential candidates are struggling to find a coherent national security argument against President Barack Obama.

In the first debate dedicated to security and foreign policy, former Massachusetts Gov. Mitt Romney took issue with Obama’s plan for drawing down troops in Afghanistan but the dispute amounted to whether some forces should stay an extra few months. Texas Gov. Rick Perry called for sanctions against the Iranian central bank. Romney and former Utah Gov. Jon Huntsman debated whether the World Trade Organization should investigate Chinese currency practices.