Persistent violence in Syria and Egypt has sharply divided senior advisers in the Obama administration over a moral dilemma: How far should the U.S. go to stop the killing when its actions could lead to war with Syria or damage relations with Egypt?

Hundreds have died in Egypt during protests brought on by the military overthrow of President Mohammed Morsi. In Syria, allegations of chemical weapons attacks on civilians by the government of President Bashar Assad come amid reports of hundreds more victims in a 2-year-old civil war that, by U.N. estimates, has already killed more than 100,000.

Pentagon leaders, including Defense Secretary Chuck Hagel and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, have argued for moderation in the U.S. response. They say that cutting off aid to Egypt would threaten key national security agreements and could rattle the peace between Egypt and Israel. They suggest that such action would cost the U.S. its leverage and even risk losing access to the Suez Canal and permission for military flights over Egypt.

Others in the administration, among them close advisers in the West Wing, have countered that the U.S. should take more decisive action to curtail the violence in Egypt as well as the sectarian war in Syria. So far, the White House has taken only incremental steps. In that vein, it’s expected to announce in the coming days the suspension of another major weapons shipment to Egypt.

The lack of a unified position – both within the Obama administration and on Capitol Hill – is giving President Barack Obama time and space for his cautious approach. But that is riling those who believe that the U.S. should put stronger pressure on Egypt’s military and take military action against Assad’s government.

Obama, nevertheless, is staunchly defending his cautious, methodical approach.

On Syria, for instance, he said in a CNN “New Day” interview broadcast Friday that the possible use of chemical weapons by Assad’s forces is a “big event of grave concern.” He said the United States is still seeking confirmation that toxic gases were used. However, Obama also said the idea that the U.S. can solve Syria’s civil war is “overstated.”

When it comes to crisis situations, whether at home or overseas, he said, “the buck stops with me.”

On Egypt, Obama said that cutting U.S. military aid to Cairo “may not reverse what the interim government does.” But he said the United States must be “very careful” about being seen as aiding and abetting actions that run contrary to the country’s values.

Asked to specifically address harsh criticism directed his way by Sen. John McCain, the Arizona Republican he defeated in the presidential campaign of 2008, Obama said he respects McCain’s passion for helping people under siege but said he must, nevertheless, move cautiously on international crises.

The next military weapons shipments for Egypt are scheduled for next month – including 10 Apache helicopters at a cost of about $500 million. Also scheduled for delivery are a number of M1A1 tank kits, including machine guns and other equipment used with the tanks, as well as some used missiles. The missiles, which have been moved and handled but not yet fired, could be used for spare parts by the Egyptian military or they could be refurbished for launching.

According to senior U.S. officials, however, the administration is expected to delay the delivery of Apache helicopters. That move, which may not come until next week, would be the second major weapons sale put on hold by the U.S. in an effort to pressure the Egyptian military to halt the bloodshed and take steps toward a more peaceful transition to democracy. The officials spoke on condition of anonymity because they were not authorized to discuss the matter by name.

To express displeasure about the Egyptian crackdown on pro-Morsi demonstrators, the U.S. suspended the delivery of four F-16 fighter jets to Egypt and canceled biennial U.S.-Egyptian military exercises planned for next month. Obama has said that the United States’ long-term cooperation with Egypt “cannot continue as usual.”

However, the U.S. military has continued shipments of thousands of spare parts for American weapons systems used by the Egyptian forces. Plans continue for sending armored bulldozers for border security, radars and missiles in the coming months.

Senate Republican leader Mitch McConnell said Thursday that he believed the U.S. had reached a “tipping point” on Egypt.

“The Egyptian military needs to let the democratic process go forward,” McConnell, R-Ky., told CNN. “I think we’re going to be voting on this again in September because it looks to me like the crackdown is not an indication that they are moving in the direction of having a new election.”

Meanwhile, the latest concerns about chemical weapons in Syria prompted a meeting of Obama’s national security team. Secretary of State John Kerry, who is on vacation, attended via video teleconference and made a flurry of telephone calls to world leaders to discuss the unrelenting bloodshed in Syria.

The United States said in June that it had conclusive evidence that Assad’s government had used chemical weapons against opposition forces. That crossed what Obama had called a “red line” and prompted a U.S. decision to send arms to Syrian rebels, including guns, ammunition and shoulder-fired, anti-tank grenades.

State Department spokeswoman Jen Psaki said that 1,000 to 1,800 people were killed near Damascus in the latest alleged chemical weapons attack. She said Obama had directed U.S. intelligence agencies to gather additional information, but “right now, we are unable to conclusively determine chemical weapons use.”

French Foreign Minister Laurent Fabius on Tuesday raised the possibility of the international community using force. Turkish Foreign Minister Ahmet Davutoglu said at a news conference in Berlin, “Several red lines have been crossed – if sanctions are not imposed immediately, then we will lose our power to deter.”

Kerry has also urged other nations to help gather information about the reports of chemical weapons attacks. And the Obama administration is expected to hold more meetings on the matter in coming days.

McCain, a leading advocate of a more aggressive U.S. response to the events in Syria, said on CNN that if Assad believes there will be no retaliation, Assad would see that “the word of the president of the United States can no longer be taken seriously.”

Top military leaders have cautioned against even limited action in Syria. Dempsey, the Joint Chiefs chairman, said in a letter this week to a congressman that the U.S. military is clearly capable of taking out Assad’s air force and shifting the balance of the war toward the armed opposition. But such an approach would plunge the U.S. into the war without offering any strategy for ending what has become a sectarian fight, he added.

In Congress, Republicans are split between hawks such as McCain and tea party isolationists such as Sens. Rand Paul of Kentucky and Ted Cruz of Texas. In between there is no clear picture either, with moderates like Sen. Bob Corker of Tennessee voicing opposition to a U.S.-enforced no-fly zone over Syria while others say it is time to act.

On Egypt, Paul, Cruz and 11 other senators voted to halt all U.S. aid to military leaders last month, but they were defeated as a majority of Republicans and all Democrats backed continued assistance. Many in both parties stressed the importance of maintaining U.S. leverage and supporting Israel’s security. Since then, however, McCain and some others have switched sides, saying U.S. funds now should be suspended given the harshness of the Egyptian government’s crackdown on Islamist opponents.

Among Democrats, Sens. Patrick Leahy of Vermont and Carl Levin of Michigan believe U.S. law compels a halt in aid to Egypt until democracy is restored. Most of their colleagues disagree. On Syria, some in Obama’s party see the president wading dangerously toward war by authorizing weapons deliveries to the rebels, while hawks and humanitarian interventionists believe he is doing too little.