RIYADH, Saudi Arabia — Highlighting a divide with the United States over whether to arm Syrian rebels, Saudi Arabia’s chief diplomat said Monday there is a moral responsibility to speed an end to the civil war, including by helping Syrians fight the regime’s ‘‘vicious killing machine.’’
‘‘Saudi Arabia will do everything in its capacity. We do believe that what is happening in Syria is a slaughter — a slaughter of innocents,’’ Prince Saud al-Faisal said during a visit by Secretary of State John Kerry. ‘‘We cannot bring ourselves to remain silent. Morally there is a duty.’’
Saudi Arabia is believed to be sending small arms and perhaps other weapons to rebels. Saud’s brother, former intelligence chief Prince Turki al-Faisal, called in January for sending heavy weapons such as antitank and antiaircraft weapons.
The Obama administration and the European Union have refused to provide weapons but agreed last week to begin sending some direct battlefield support for the rebels fighting the government of President Bashar al-Assad.
The United States will provide only food and medicine for now, arguing that weapons could too easily be diverted to Islamist militants working alongside what Kerry on Monday called the ‘‘moderate, legitimate opposition.’’
Syria is awash in weapons, some supplied to the government by Iran and Russia. Rebels are capturing government stockpiles to augment arms supplied from other countries.
Kerry did not directly answer a question about whether weapons supplied by Saudi Arabia, a key counterterrorism partner, are part of the problem.
‘‘There is no guarantee that one weapon or another might not, at some point in time, fall into the wrong hands,’’ Kerry said a news conference with the veteran Saudi diplomat.
But the Syrian opposition has demonstrated that it can direct support to the right fighters, and the fighters are making good use of what they are already receiving, he said.
Kerry gave no specifics about who is sending what. Syrian Opposition Coalition leader Mouaz al-Khatib, standing alongside Kerry last week, angrily said outsiders seem more focused on the Islamists than on the true enemy: Assad.
‘‘For its part, the kingdom stressed the importance of enabling the Syrian people to exercise its legitimate right to defend itself against the regime’s vicious killing machine,’’ Saud said after meeting with Kerry.
Saud is the world’s longest-serving foreign minister, appointed in 1975. He is known as a shrewd observer of international dealings, and one not shy to tweak the American government in public.
Monday’s joint appearance was cordial. Kerry saw Saud for lengthy meetings over two days that were focused on counterterrorism cooperation and the shared view that Iran poses a threat of developing nuclear weapons.
Kerry did not meet with Saudi King Abdullah. He saw diplomats from several other Persian Gulf nations who were attending a regional conference, and he had a hastily arranged lunch Monday with visiting Palestinian President Mahmoud Abbas.
The Abbas meeting comes in lieu of a visit to Israel and the Palestinian territories on this trip, Kerry’s first as secretary.
President Obama is visiting Jerusalem and Ramallah later this month, with Kerry in tow, and the White House viewed an interim stop by Kerry as potentially diluting the impact of Obama’s visit.
Although Kerry said the United States won’t ‘‘plunk down a plan’’ for Middle East peace on that trip, Obama will hope to jump-start talks.
Kerry is also scheduled to visit the United Arab Emirates and Qatar before returning to Washington on Wednesday.
The United States and Saudi Arabia also have a difference of opinion over the value of continued negotiations with Iran over its nuclear program.
Although both Kerry and Saud stressed Monday that they prefer to use diplomacy to resolve the crisis, Saud made a point of saying that Iran’s nuclear program continues ‘‘unabated’’ while talks continue.
Taking a much tougher line on Iran than he did immediately following apparently cordial talks in Kazakhstan last week, Kerry ruled out negotiation with Iran over any subject apart from its disputed nuclear development program.
He said the window of opportunity for a diplomatic resolution of questions over Iran’s nuclear work ‘‘cannot by definition remain open indefinitely.’’