BAGHDAD (AFP) - Baghdad and Tehran pledged on Wednesday to strengthen ties and put the past behind them, even as Washington accuses Iran of supplying new and more lethal weapons to anti-US militias. Iran and Iraq, which fought a 1980-1988 war that was one of the bloodiest conflicts of the past century, killing an estimated one million people, have drawn closer since the US-led invasion of 2003. But US officials have expressed concern at the Islamic republic's growing influence in Iraq, which is strategically important to both Tehran and Washington.