Sectarian rioting rocked north Belfast last week as Protestant marching season raised tensions between hostile communities. The British government began sending in 1,600 additional troops to support local police, making the total British military presence in Northern Ireland more than 15,000 soldiers. Drumcree in Portadown has been a flash point the last few years and may be so again, with authorities likely to prohibit Protestants from marching down Garvaghy Road. As in past years, this could lead to massive protests, and possible violence. Further, assembly leader David Trimble again vowed to resign July 1 if the IRA doesn’t begin disarming. If he does, a political crisis could add to the tensions.