Nonsingular Ricci flow on a noncompact manifold in dimension three

We consider the Ricci flow $\frac{\mathrm{\partial }}{\mathrm{\partial }t}g=-2Ric$ on the 3-dimensional complete noncompact manifold $(M,g(0))$ with non-negative curvature operator, i.e., $Rm\ge 0,\mathrm{\mid }Rm(p)\mathrm{\mid }\to 0,asd(o,p)\to 0.$ We prove that the Ricci flow on such a manifold is nonsingular in any finite time.