President Donald Trump is weighing a strategy that could allow more aggressive U.S. responses to Iran's forces, its Shiite Muslim proxies in Iraq and Syria, and its support for militant groups, according to six current and former U.S. officials.

The proposal was prepared by Defense Secretary James Mattis, Secretary of State Rex Tillerson, national security adviser H.R. McMaster and other top officials, and presented to Trump at a National Security Council meeting on Friday, the sources said.

It could be agreed and made public before the end of September, two of the sources said. All of the sources are familiar with the draft and requested anonymity because Trump has yet to act on it.