"The enemy [Taliban] is under pressure, they have a loss of leadership and have become increasingly fractious", Mr Mattis said.
The Senate Armed Services Committee "still does not know numerous crucial details of the strategy".
Defense Secretary Jim Mattis said Tuesday that the more than 3,000 additional troops being deployed to Afghanistan will effectively be on "combat duty" as they support Afghan security forces on the front lines. But the U.S. president recertified the deal in July.
Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, says the U.S.is spending $12.5 billion overall to wage America's longest war.
Indeed, several Republican lawmakers have voiced skepticism over the president's decertification strategy, including the GOP chairmen of the Senate and House foreign relations committees, Senator Bob Corker of Tennessee and Rep. Ed Royce of California, as well as Senators Rand Paul of Kentucky, Jeff Flake of Arizona and Tom Cotton of Arkansas.
US President Donald Trump has desperately sought a pretext to scrap or weaken the 2015 nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA), and get rid of the limits it imposes on the US ability to pursue more hostile policies against Iran. We must be well-informed. The strategy hits upon larger themes of Trump's August 21 address to the American people, when he pledged to adopt a conditions-based approach for withdrawal from Afghanistan that focuses on pressuring Pakistan to crack down on terror safe havens.
Brexit is our core task says new Ukip leader Henry Bolton
The party won no seats and just 1.8% of the national vote, down from the 12.6% of the vote it won in 2015. In his victory speech at Ukip conference in Torquay, he called on members to rally around the party.
Saudi Arabia lifts ban on women drivers
Others argued that allowing women to drive would lead to promiscuity and the collapse of the Saudi family. And we were privileged women who had money and cars for drivers.
Star Wars Battlefront II trailer reveals locations, heroes and game modes
Like with the characters, you'll be able to earn Battle Points to unlock your favorite " hero ships" like the Millennium Falcon. In termsof game modes, Strike is a PvP battle featuring two teams of eight players, both competing in objective-based missions.
European ambassadors speaking in Washington last week said they would do everything possible to protect companies based in Europe and that continue to do business with Iran, from reimposed US sanctions. He indicated that after an effective military effort it eventually may be possible to reach a political settlement in Afghanistan that includes elements of the Taliban.
Dunford told the committee that it's clear to him that Pakistan's intelligence service has connections to the terrorist groups.
Trump must notify Congress every 90 days whether Iran is abiding by the accord and whether the lifting of sanctions against Tehran is in the United States national interest.
"I believe., absent indications to the contrary, it is something that the president should consider staying with", Mattis added.
Trump is weighing whether the deal serves USA security interests as he faces a mid-October deadline for certifying that Iran is complying with the pact, a decision that could sink an agreement strongly supported by the other powers that negotiated it.
The Trump administration has twice so far certified Iran's compliance with the deal, but if he refuses to do that for a third time, then the Republican-controlled Congress will have 60 days to decide whether to re-impose sanctions waived under the deal.