The world’s top two crude-oil producers pledged to cooperate to stabilize global markets, while failing to announce any specific measures to bolster prices. “We have a number of tools at our disposal for joint actions,” Russian Energy Minister Alexander Novak said Monday following a meeting with his Saudi counterpart Khalid Al-Falih at the G-20 summit in China. Both agree that an output freeze would be the most constructive instrument, he said. Investec Bank Chief Economist Philip Shaw discusses on "Countdown."