WASHINGTON (AP) ― The Obama administration opened the door slightly Tuesday to international military assistance for Syria’s rebels, with officials saying new tactics may have to be explored if President Bashar Assad continues to defy pressure to halt a brutal crackdown on dissenters.

In coordinated messages, the White House and State Department said they still hope for a political solution. But faced with the daily onslaught by the Assad regime against Syrian civilians, officials dropped the administration’s previous strident opposition to arming anti-regime forces. It remained unclear, though, what, if any, role the U.S. might play in providing such aid.

“We don’t want to take actions that would contribute to the further militarization of Syria because that could take the country down a dangerous path,’’ White House press secretary Jay Carney told reporters. “But we don’t rule out additional measures if the international community should wait too long and not take the kind of action that needs to be taken.”

The administration previously has said flatly that more weapons are not the answer to the Syrian situation. There had been no mention of “additional measures.”

At the State Department, spokeswoman Victoria Nuland used nearly identical language to describe the administration’s evolving position.

“From our perspective, we don’t believe that it makes sense to contribute now to the further militarization of Syria,” she told reporters. “What we don’t want to see is the spiral of violence increase. That said, if we can’t get Assad to yield to the pressure that we are all bringing to bear, we may have to consider additional measures.”

Neither Carney nor Nuland would elaborate on what “additional measures” might be taken, but there have been growing calls, including from some in Congress, for the international community to arm the rebels. Most suggestions to that effect have foreseen Arab nations such as Qatar, the United Arab Emirates and Saudi Arabia, and not the West, possibly providing military assistance.

Other officials said discussions are now under way about adding a military component to a package of humanitarian and political aid to the opposition that is to be discussed at a major international conference on Syria this week in Tunisia.

More than 70 countries have been invited to meet Friday in Tunisia for a “Friends of Syria” meeting, which follows the failure of the U.N. Security Council to endorse an Arab plan that would have seen Assad removed from power.

The meeting of the “Friends of Syria” in Tunis is unlikely to produce decisions on military aid or even recognition of Syria’s disparate opposition groups, according to U.S. officials. But countries are considering creating large stockpiles of humanitarian aid along Syria’s borders, the officials said.

U.S. officials stressed that discussion of military assistance still is preliminary.

The officials spoke on condition of anonymity due to the sensitive nature of the diplomacy.

To maintain the pressure against Assad, Washington is trying to keep as many countries as possible involved in the international coordination against Syria’s government, even if there is no consensus strategy on arming the rebels.

This week’s talks will seek to clarify some of the confusion. The U.S. is trying to get a clearer picture of what promises countries such as Syria’s Arab neighbors are making to elements of the opposition; which rebels each government might support; and some agreement on what types of assistance would be helpful or damaging.

The backdrop to the discussions is the increasing fear that Syria could descend into an all-out civil war.

Meanwhile, the Pentagon on Tuesday disputed reports that Iranian ships docked at a Syrian port over the weekend.

Iranian state-run Press TV said Saturday that an Iranian navy destroyer and a supply ship had docked in the port of Tartus to provide training to ally Syria’s naval forces, as Syria tries to crush the opposition movement.

Defense Department press secretary George Little said Tuesday the U.S. military saw no indication that the ships docked or delivered any cargo. Little said Tehran’s ships went through the Suez Canal and now appear to be going back through the canal again.