Cook the noodles in large pot of boiling salted water according to package directions. Drain and set aside.
Meanwhile, heat the oil in a large, deep skillet over medium-high heat. Add the garlic and chili paste; cook for 30 seconds. Add the chicken, fish sauce, soy sauce, sugar and bell peppers. Cook, stirring, until the chicken is cooked through, 4 to 6 minutes.
Add the noodles and tomatoes and toss to coat. Transfer to a large platter, sprinkle with basil and serve.